Nonrelativistic Conformed Symmetry in 2 + 1 Dimensional Field Theory.
Bergman, Oren
This thesis is devoted to the study of conformal invariance and its breaking in non-relativistic field theories. It is a well known feature of relativistic field theory that theories which are conformally invariant at the classical level can acquire a conformal anomaly upon quantization and renormalization. The anomaly appears through the introduction of an arbitrary, but dimensionful, renormalization scale. One does not usually associate the concepts of renormalization and anomaly with nonrelativistic quantum mechanics, but there are a few examples where these concepts are useful. The most well known case is the two-dimensional delta -function potential. In two dimensions the delta-function scales like the kinetic term of the Hamiltonian, and therefore the problem is classically conformally invariant. Another example of classical conformal invariance is the famous Aharonov-Bohm (AB) problem. In that case each partial wave sees a 1/r^2 potential. We use the second quantized formulation of these problems, namely the nonrelativistic field theories, to compute Green's functions and derive the conformal anomaly. In the case of the AB problem we also solve an old puzzle, namely how to reproduce the result of Aharonov and Bohm in perturbation theory. The thesis is organized in the following manner. Chapter 1 is an introduction to nonrelativistic field theory, nonrelativistic conformal invariance, contact interactions and the AB problem. In Chapter 2 we discuss nonrelativistic scalar field theory, and how its quantization produces the anomaly. Chapter 3 is devoted to the AB problem, and the resolution of the perturbation puzzle. In Chapter 4 we generalize the discussion of Chapter 3 to particles carrying nonabelian charges. The structure of the nonabelian theory is much richer, and deserves a separate discussion. We also comment on the issues of forward scattering and single -valuedness of wavefunctions, which are important for Chapter 3 as well. (Copies available
Introduction to two dimensional conformal and superconformal field theory
International Nuclear Information System (INIS)
Shenker, S.H.
1986-01-01
Some of the basic properties of conformal and superconformal field theories in two dimensions are discussed in connection with the string and superstring theories built from them. In the first lecture the stress-energy tensor, the Virasoro algebra, highest weight states, primary fields, operator products coefficients, bootstrap ideas, and unitary and degenerate representations of the Virasoro algebra are discussed. In the second lecture the basic structure of superconformal two dimensional field theory is sketched and then the Ramond Neveu-Schwarz formulation of the superstring is described. Some of the issues involved in constructing the fermion vertex in this formalism are discussed
Twistors and four-dimensional conformal field theory
International Nuclear Information System (INIS)
Singer, M.A.
1990-01-01
This is a report (with technical details omitted) on work concerned with generalizations to four dimensions of two-dimensional Conformed Field Theory. Accounts of this and related material are contained elsewhere. The Hilbert space of the four-dimensional theory has a natural interpretation in terms of massless spinor fields on real Minkowski space. From the twistor point of view this follows from the boundary CR-manifold P being precisely the space of light rays in real compactified Minkowski space. All the amplitudes can therefore be regarded as defined on Hilbert spaces built from Lorentzian spinor fields. Thus the twistor picture provides a kind of halfway house between the Lorentzian and Euclidean field theories. (author)
International Nuclear Information System (INIS)
Chung, Stephen-wei.
1993-01-01
The authors first construct new parafermions in two-dimensional conformal field theory, generalizing the Z L parafermion theories from integer L to rational L. These non-unitary parafermions have some novel features: an infinite number of currents with negative conformal dimensions for most (if not all) of them. String functions of these new parafermion theories are calculated. They also construct new representations of N = 2 superconformal field theories, whose characters are obtained in terms of these new string functions. They then generalize Felder's BRST cohomology method to construct the characters and branching functions of the SU(2) L x SU(2) K /SU(2) K+L coset theories, where one of the (K,L) is an integer. This method of obtaining the branching functions also serves as a check of their new Z L parafermion theories. The next topic is the Lagrangian formulation of conformal field theory. They construct a chiral gauged WZW theory where the gauge fields are chiral and belong to the subgroups H L and H R , which can be different groups. This new construction is beyond the ordinary vector gauged WZW theory, whose gauge group H is a subgroup of both G L and G R . In the special case where H L = H R , the quantum theory of chiral gauged WZW theory is equivalent to that of the vector gauged WZW theory. It can be further shown that the chiral gauged WZW theory is equivalent to [G L /H L ](z) direct-product [G R /H R ](bar z) coset models in conformal field theory. In the second half of this thesis, they construct topological lattice field theories in three dimensions. After defining a general class of local lattice field theories, they impose invariance under arbitrary topology-preserving deformations of the underlying lattice, which are generated by two local lattice moves. Invariant solutions are in one-to-one correspondence with Hopf algebras satisfying a certain constraint
A geometrical approach to two-dimensional Conformal Field Theory
Dijkgraaf, Robertus Henricus
1989-09-01
manifold obtained as the quotient of a smooth manifold by a discrete group. In Chapter 6 our considerations will be of a somewhat complementary nature. We will investigate models with central charge c = 1 by deformation techniques. The central charge is a fundamental parameter in any conformal invariant model, and the value c = 1 is of considerable interest, since it forms in many ways a threshold value. For c 1 is still very much terra incognita. Our results give a partial classification for the intermediate case of c = 1 models. The formulation of these c = 1 CFT's on surfaces of arbitrary topology is central in Chapter 7. Here we will provide many explicit results that provide illustrations for our more abstract discussions of higher genus quantities in Chapters 3 and 1. Unfortunately, our calculations will become at this point rather technical, since we have to make extensive use of the mathematics of Riemann surfaces and their coverings. Finally, in Chapter 8 we leave the two-dimensional point of view that we have been so loyal to up to then , and ascend to threedimensions where we meet topological gauge theories. These so-called Chern-Simons theories encode in a very economic way much of the structure of two-dimensional (rational) conformal field theories, and this direction is generally seen to be very promising. We will show in particular how many of our results of Chapter 5 have a natural interpretation in three dimensions.
Braided structure in 4-dimensional conformal quantum field theory
International Nuclear Information System (INIS)
Schroer, Bert
2001-03-01
Higher dimensional conformal QFT possesses an intersting braided structure which different from the d=1+1 models, is restricted to the timelike region and therefore easily escapes euclidean action methods. It lies behind the spectrum of anamalous which may be viewed as a kind of substitute for a missing particle interpretation in the presence of interactions. (author)
An algebraic approach towards the classification of 2 dimensional conformal field theories
International Nuclear Information System (INIS)
Bouwknegt, P.G.
1988-01-01
This thesis treats an algebraic method for the construction of 2-dimensional conformal field theories. The method consists of the study of the representation theory of the Virasoro algebra and suitable extensions of this. The classification of 2-dimensional conformal field theories is translated into the classification of combinations of representations which satisfy certain consistence conditions (unitarity and modular invariance). For a certain class of 2-dimensional field theories, namely the one with central charge c = 1 from the theory of Kac-Moody algebra's. there exist indications, but as yet mainly hope, that this construction will finally lead to a classification of 2-dimensional conformal field theories. 182 refs.; 2 figs.; 26 tabs
BRST structure of two dimensional conformal field theories
International Nuclear Information System (INIS)
Rivelles, V.O.
1987-09-01
We present a procedure to obtain the BRST charge for the representations of the Virassoro algebra. For C ≤ 1 the BRST charge has in general terms containing products of more than three ghosts. It is nilpotent for any allowed value of the central charge and conformal weight of the representation. (Author) [pt
Infinite additional symmetries in two-dimensional conformal quantum field theory
International Nuclear Information System (INIS)
Zamolodchikov, A.B.
1986-01-01
This paper investigates additional symmetries in two-dimensional conformal field theory generated by spin s = 1/2, 1,...,3 currents. For spins s = 5/2 and s = 3, the generators of the symmetry form associative algebras with quadratic determining relations. ''Minimal models'' of conforma field theory with such additional symmetries are considered. The space of local fields occurring in a conformal field theory with additional symmetry corresponds to a certain (in general, reducible) representation of the corresponding algebra of the symmetry
Infinite-dimensional Lie algebras in 4D conformal quantum field theory
International Nuclear Information System (INIS)
Bakalov, Bojko; Nikolov, Nikolay M; Rehren, Karl-Henning; Todorov, Ivan
2008-01-01
The concept of global conformal invariance (GCI) opens the way of applying algebraic techniques, developed in the context of two-dimensional chiral conformal field theory, to a higher (even) dimensional spacetime. In particular, a system of GCI scalar fields of conformal dimension two gives rise to a Lie algebra of harmonic bilocal fields, V M (x, y), where the M span a finite dimensional real matrix algebra M closed under transposition. The associative algebra M is irreducible iff its commutant M' coincides with one of the three real division rings. The Lie algebra of (the modes of) the bilocal fields is in each case an infinite-dimensional Lie algebra: a central extension of sp(∞,R) corresponding to the field R of reals, of u(∞, ∞) associated with the field C of complex numbers, and of so*(4∞) related to the algebra H of quaternions. They give rise to quantum field theory models with superselection sectors governed by the (global) gauge groups O(N), U(N) and U(N,H)=Sp(2N), respectively
Diagnosing Chaos Using Four-Point Functions in Two-Dimensional Conformal Field Theory.
Roberts, Daniel A; Stanford, Douglas
2015-09-25
We study chaotic dynamics in two-dimensional conformal field theory through out-of-time-order thermal correlators of the form ⟨W(t)VW(t)V⟩. We reproduce holographic calculations similar to those of Shenker and Stanford, by studying the large c Virasoro identity conformal block. The contribution of this block to the above correlation function begins to decrease exponentially after a delay of ~t_{*}-(β/2π)logβ^{2}E_{w}E_{v}, where t_{*} is the fast scrambling time (β/2π)logc and E_{w},E_{v} are the energy scales of the W,V operators.
Relative entropy of excited states in two dimensional conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Sárosi, Gábor [Department of Theoretical Physics, Institute of Physics, Budapest University of Technology,Budapest, H-1521 (Hungary); Ugajin, Tomonori [Kavli Institute for Theoretical Physics, University of California,Santa Barbara,CA 93106 (United States)
2016-07-21
We study the relative entropy and the trace square distance, both of which measure the distance between reduced density matrices of two excited states in two dimensional conformal field theories. We find a general formula for the relative entropy between two primary states with the same conformal dimension in the limit of a single small interval and find that in this case the relative entropy is proportional to the trace square distance. We check our general formulae by calculating the relative entropy between two generalized free fields and the trace square distance between the spin and disorder operators of the critical Ising model. We also give the leading term of the relative entropy in the small interval expansion when the two operators have different conformal dimensions. This turns out to be universal when the CFT has no primaires lighter than the stress tensor. The result reproduces the previously known special cases.
Extensions of conformal symmetry in two-dimensional quantum field theory
International Nuclear Information System (INIS)
Schoutens, C.J.M.
1989-01-01
Conformal symmetry extensions in a two-dimensional quantum field theory are the main theme of the work presented in this thesis. After a brief exposition of the formalism for conformal field theory, the motivation for studying extended symmetries in conformal field theory is presented in some detail. Supersymmetric extensions of conformal symmetry are introduced. An overview of the algebraic superconformal symmetry is given. The relevance of higher-spin bosonic extensions of the Virasoro algebra in relation to the classification program for so-called rational conformal theories is explained. The construction of a large class of bosonic extended algebras, the so-called Casimir algebras, are presented. The representation theory of these algebras is discussed and a large class of new unitary models is identified. The superspace formalism for O(N)-extended superconformal quantum field theory is presented. It is shown that such theories exist for N ≤ 4. Special attention is paid to the case N = 4 and it is shown that the allowed central charges are c(n + ,n - ) = 6n + n - /(n + ,n - ), where n + and n - are positive integers. A different class of so(N)-extended superconformal algebras is analyzed. The representation theory is studied and it is established that certain free field theories provide realizations of the algebras with level S = 1. Finally the so-called BRST construction for extended conformal algebras is considered. A nilpotent BRST charge is constructed for a large class of algebras, which contains quadratically nonlinear algebras that fall outside the traditional class if finitely generated Lie (super)algebras. The results are especially relevant for the construction of string models based on extended conformal symmetry. (author). 118 refs.; 7 tabs
Three-dimensional conformal pancreas treatment: comparison of four- to six-field techniques
International Nuclear Information System (INIS)
Higgins, Patrick D.; Sohn, Jason W.; Fine, Robert M.; Schell, Michael C.
1995-01-01
Purpose: We compare practical conformal treatment approaches to pancreatic cancer using 6 and 18 MV photons and contrast those approaches against standard techniques. Methods and Materials: A four-field conformal technique for treating pancreas cancer has been developed using nonopposed 18 MV photons. This approach has been extended to 6 MV photon application by the addition of one to two fields. These techniques have been optimized to increase sparing of normal liver and bowel, compared with opposed-field methods, to improve patient tolerance of high doses. In this study we compare these techniques in a simulated tumor model in a cylindrical phantom. Dose-volume analysis is used to quantify differences between the conformal, nonopposed techniques with conformal, opposed field methods. This model is also used to evaluate the effect of 1-2 cm setup errors on dose-volume coverage. Results: Dose-volume analysis demonstrates that five-to-six field conformal treatments using 6 MV photons provides similar or better dose coverage and normal tissue sparing characteristics as an optimized 18 MV, four-field approach when 1-2 cm margins are included for setup uncertainty. All approaches using nonopposed beam geometry provide significant reduction in the volume of tissue encompassed by the 30-50% isodose surfaces, as compared with four-field box techniques. Conclusions: Three-dimensional (3D) conformal treatments can be designed that significantly improve dose-volume characteristics over conventional treatment designs without costing unacceptable amounts of machine time. Further, deep intraabdominal sites can be adequately accessed and treated on intermediate energy machines with a relatively moderate increase in machine time
Two-dimensional conformal field theory and beyond. Lessons from a continuing fashion
International Nuclear Information System (INIS)
Todorov, I.
2000-01-01
Two-dimensional conformal field theory (CFT) has several sources: the search for simple examples of quantum field theory, tile description of surface critical phenomena, the study of (super)string vacua (which made it particularly fashionable). In the present overview of tile subject we emphasize the role of CFT in bridging the gap between mathematics and quantum field theory and discuss some new physical concepts that emerged in the study of CFT models: anomalous dimensions, rational CFT, braid group statistics. In an aside, at tile end of the paper, we share tile misgivings, recently expressed by Penrose, about some dominant trends in fundamental theoretical physics. (author)
Conformal field theory in conformal space
International Nuclear Information System (INIS)
Preitschopf, C.R.; Vasiliev, M.A.
1999-01-01
We present a new framework for a Lagrangian description of conformal field theories in various dimensions based on a local version of d + 2-dimensional conformal space. The results include a true gauge theory of conformal gravity in d = (1, 3) and any standard matter coupled to it. An important feature is the automatic derivation of the conformal gravity constraints, which are necessary for the analysis of the matter systems
Infinite additional symmetries in the two-dimensional conformal quantum field theory
International Nuclear Information System (INIS)
Apikyan, S.A.
1987-01-01
Additional symmetries in the two-dimensional conformal field theory, generated by currents (2,3/2,5/2) and (2,3/2,3) have been studied. It has been shown that algebra (2,3/2,5/2) is the direct product of algebras (2,3/2) and (2,5/2), and algebra (2,3/2,3) is the direct product of algebras (2,3/2) and (2,3). Associative algebra, formed by multicomponent symmetry generators of spin 3 for SO(3) has also been found
Algebraic conformal field theory
International Nuclear Information System (INIS)
Fuchs, J.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica
1991-11-01
Many conformal field theory features are special versions of structures which are present in arbitrary 2-dimensional quantum field theories. So it makes sense to describe 2-dimensional conformal field theories in context of algebraic theory of superselection sectors. While most of the results of the algebraic theory are rather abstract, conformal field theories offer the possibility to work out many formulae explicitly. In particular, one can construct the full algebra A-bar of global observables and the endomorphisms of A-bar which represent the superselection sectors. Some explicit results are presented for the level 1 so(N) WZW theories; the algebra A-bar is found to be the enveloping algebra of a Lie algebra L-bar which is an extension of the chiral symmetry algebra of the WZW theory. (author). 21 refs., 6 figs
Fermionic field perturbations of a three-dimensional Lifshitz black hole in conformal gravity
Energy Technology Data Exchange (ETDEWEB)
Gonzalez, P.A. [Facultad de Ingenieria y Ciencias, Universidad Diego Portales, Santiago (Chile); Vasquez, Yerko; Villalobos, Ruth Noemi [Universidad de La Serena, Departamento de Fisica y Astronomia, Facultad de Ciencias, La Serena (Chile)
2017-09-15
We study the propagation of massless fermionic fields in the background of a three-dimensional Lifshitz black hole, which is a solution of conformal gravity. The black-hole solution is characterized by a vanishing dynamical exponent. Then we compute analytically the quasinormal modes, the area spectrum, and the absorption cross section for fermionic fields. The analysis of the quasinormal modes shows that the fermionic perturbations are stable in this background. The area and entropy spectrum are evenly spaced. In the low frequency limit, it is observed that there is a range of values of the angular momentum of the mode that contributes to the absorption cross section, whereas it vanishes in the high frequency limit. In addition, by a suitable change of variables a gravitational soliton can also be obtained and the stability of the quasinormal modes are studied and ensured. (orig.)
Two dimensional infinite conformal symmetry
International Nuclear Information System (INIS)
Mohanta, N.N.; Tripathy, K.C.
1993-01-01
The invariant discontinuous (discrete) conformal transformation groups, namely the Kleinian and Fuchsian groups Gamma (with an arbitrary signature) of H (the Poincare upper half-plane l) and the unit disc Delta are explicitly constructed from the fundamental domain D. The Riemann surface with signatures of Gamma and conformally invariant automorphic forms (functions) with Peterson scalar product are discussed. The functor, where the category of complex Hilbert spaces spanned by the space of cusp forms constitutes the two dimensional conformal field theory. (Author) 7 refs
Relative entanglement entropies in 1+1-dimensional conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Ruggiero, Paola; Calabrese, Pasquale [International School for Advanced Studies (SISSA) and INFN,Via Bonomea 265, 34136, Trieste (Italy)
2017-02-08
We study the relative entanglement entropies of one interval between excited states of a 1+1 dimensional conformal field theory (CFT). To compute the relative entropy S(ρ{sub 1}∥ρ{sub 0}) between two given reduced density matrices ρ{sub 1} and ρ{sub 0} of a quantum field theory, we employ the replica trick which relies on the path integral representation of Tr(ρ{sub 1}ρ{sub 0}{sup n−1}) and define a set of Rényi relative entropies S{sub n}(ρ{sub 1}∥ρ{sub 0}). We compute these quantities for integer values of the parameter n and derive via the replica limit the relative entropy between excited states generated by primary fields of a free massless bosonic field. In particular, we provide the relative entanglement entropy of the state described by the primary operator i∂ϕ, both with respect to the ground state and to the state generated by chiral vertex operators. These predictions are tested against exact numerical calculations in the XX spin-chain finding perfect agreement.
International Nuclear Information System (INIS)
Friedan, D.H.; Martinec, E.J.; Shenker, S.H.
1988-12-01
The present contract supported work by Daniel H. Frieden, Emil J, Martinec and Stephen H. Shenker (principal investigators), Research Associates, and graduate students in theoretical physics at the University of Chicago. Research has been conducted in areas of string theory and two dimensional conformal and superconformal field theory. The ultimate objectives have been: to expose the fundamental structure of string theory so as to eventually make possible effective nonperturbative calculations and thus a comparison of sting theory with experiment, the complete classification of all two dimensional conformal and superconformal field theories thus giving a complete description of all classical ground states of string and of all possible two (and 1 + 1) dimensional critical phenomena, and the development of methods to describe, construct and solve two dimensional field theories. Work has also been done on skyrmion and strong interaction physics
International Nuclear Information System (INIS)
Kosztyla, Robert; Pierce, Greg; Ploquin, Nicolas; Roumeliotis, Michael; Schinkel, Colleen
2016-01-01
Purpose: To determine the source of systematic monitor unit (MU) calculation discrepancies between RadCalc and Eclipse treatment planning software for three-dimensional conformal radiotherapy field-in-field breast treatments. Methods: Data were reviewed for 28 patients treated with a field-in-field breast technique with MU calculations from RadCalc that were larger than MU calculations from Eclipse for at least one field. The distance of the calculation point from the jaws was measured in each field’s beam’s-eye-view and compared with the percentage difference in MU (%ΔMU) between RadCalc and Eclipse. 10×10, 17×13 and 20×20 cm 2 beam profiles were measured using the Profiler 2 diode array for 6-MV photon beams and compared with profiles calculated with Eclipse and RadCalc using a gamma analysis (3%, 3 mm). Results: The mean %ΔMU was 1.3%±0.3%. There was a statistically-significant correlation between %ΔMU and the distance of the calculation point from the Y jaw (r=−0.43, p<0.001). RadCalc profiles differed from measured profiles, especially near the jaws. The gamma pass rate for 6-MV fields of 17×13 cm 2 field size was 95%±1% for Eclipse-generated profiles and 53%±20% for RadCalc-generated profiles (p=0.01). Conclusions: Calculations using RadCalc for field-in-field breast plans resulted in MUs that were larger than expected from previous clinical experience with wedged plans with calculation points far from the jaws due to the position of the calculation point near the jaws in the beam’s-eye-view of each field.
Energy Technology Data Exchange (ETDEWEB)
Kosztyla, Robert; Pierce, Greg; Ploquin, Nicolas; Roumeliotis, Michael; Schinkel, Colleen [Tom Baker Cancer Centre, Calgary, AB, Tom Baker Cancer Centre, Tom Baker Cancer Centre, Tom Baker Cancer Centre, Calgary, AB, Tom Baker Cancer Centre, Calgary, AB (Canada)
2016-08-15
Purpose: To determine the source of systematic monitor unit (MU) calculation discrepancies between RadCalc and Eclipse treatment planning software for three-dimensional conformal radiotherapy field-in-field breast treatments. Methods: Data were reviewed for 28 patients treated with a field-in-field breast technique with MU calculations from RadCalc that were larger than MU calculations from Eclipse for at least one field. The distance of the calculation point from the jaws was measured in each field’s beam’s-eye-view and compared with the percentage difference in MU (%ΔMU) between RadCalc and Eclipse. 10×10, 17×13 and 20×20 cm{sup 2} beam profiles were measured using the Profiler 2 diode array for 6-MV photon beams and compared with profiles calculated with Eclipse and RadCalc using a gamma analysis (3%, 3 mm). Results: The mean %ΔMU was 1.3%±0.3%. There was a statistically-significant correlation between %ΔMU and the distance of the calculation point from the Y jaw (r=−0.43, p<0.001). RadCalc profiles differed from measured profiles, especially near the jaws. The gamma pass rate for 6-MV fields of 17×13 cm{sup 2} field size was 95%±1% for Eclipse-generated profiles and 53%±20% for RadCalc-generated profiles (p=0.01). Conclusions: Calculations using RadCalc for field-in-field breast plans resulted in MUs that were larger than expected from previous clinical experience with wedged plans with calculation points far from the jaws due to the position of the calculation point near the jaws in the beam’s-eye-view of each field.
Superspace conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Quella, Thomas [Koeln Univ. (Germany). Inst. fuer Theoretische Physik; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-07-15
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Superspace conformal field theory
International Nuclear Information System (INIS)
Quella, Thomas
2013-07-01
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Superintegrability of d-dimensional conformal blocks
International Nuclear Information System (INIS)
Isachenkov, Mikhail
2016-02-01
We observe that conformal blocks of scalar 4-point functions in a d-dimensional conformal field theory can mapped to eigenfunctions of a 2-particle hyperbolic Calogero-Sutherland Hamiltonian. The latter describes two coupled Poeschl-Teller particles. Their interaction, whose strength depends smoothly on the dimension d, is known to be superintegrable. Our observation enables us to exploit the rich mathematical literature on Calogero-Sutherland models in deriving various results for conformal field theory. These include an explicit construction of conformal blocks in terms of Heckman-Opdam hypergeometric functions and a remarkable duality that relates the blocks of theories in different dimensions.
Superintegrability of d-dimensional conformal blocks
Energy Technology Data Exchange (ETDEWEB)
Isachenkov, Mikhail [Weizmann Institute of Science, Rehovot (Israel). Dept. of Particle Physics and Astronomy; Schomerus, Volker [DESY Theory Group, Hamburg (Germany)
2016-02-15
We observe that conformal blocks of scalar 4-point functions in a d-dimensional conformal field theory can mapped to eigenfunctions of a 2-particle hyperbolic Calogero-Sutherland Hamiltonian. The latter describes two coupled Poeschl-Teller particles. Their interaction, whose strength depends smoothly on the dimension d, is known to be superintegrable. Our observation enables us to exploit the rich mathematical literature on Calogero-Sutherland models in deriving various results for conformal field theory. These include an explicit construction of conformal blocks in terms of Heckman-Opdam hypergeometric functions and a remarkable duality that relates the blocks of theories in different dimensions.
Conformal field theories and critical phenomena
International Nuclear Information System (INIS)
Xu, Bowei
1993-01-01
In this article we present a brief review of the conformal symmetry and the two dimensional conformal quantum field theories. As concrete applications of the conformal theories to the critical phenomena in statistical systems, we calculate the value of central charge and the anomalous scale dimensions of the Z 2 symmetric quantum chain with boundary condition. The results are compatible with the prediction of the conformal field theories
Axiomatic conformal field theory
International Nuclear Information System (INIS)
Gaberdiel, M.R.; Goddard, P.
2000-01-01
A new rigourous approach to conformal field theory is presented. The basic objects are families of complex-valued amplitudes, which define a meromorphic conformal field theory (or chiral algebra) and which lead naturally to the definition of topological vector spaces, between which vertex operators act as continuous operators. In fact, in order to develop the theory, Moebius invariance rather than full conformal invariance is required but it is shown that every Moebius theory can be extended to a conformal theory by the construction of a Virasoro field. In this approach, a representation of a conformal field theory is naturally defined in terms of a family of amplitudes with appropriate analytic properties. It is shown that these amplitudes can also be derived from a suitable collection of states in the meromorphic theory. Zhu's algebra then appears naturally as the algebra of conditions which states defining highest weight representations must satisfy. The relationship of the representations of Zhu's algebra to the classification of highest weight representations is explained. (orig.)
High energy asymptotics of multi-colour QCD and two-dimensional conformal field theories
International Nuclear Information System (INIS)
Lipatov, L.N.; Deutsches Elektronen-Synchrotron
1993-04-01
In the multi-colour limit of perturbative QCD the holomorphic factorization of wave functions of compound states of n reggeized gluons in the impact parameter space is shown. The conformally invariant Hamiltonian for each holomorphic factor has a nontrivial integral of motion. The odderon in QCD is the simplest example of the composite system with these properties. (orig.)
Parafermionic conformal field theory
International Nuclear Information System (INIS)
Kurak, V.
1989-09-01
Conformal parafermionic field theories are reviewed with emphasis on the computation of their OPE estructure constants. It is presented a simple computational of these for the Z(N) parafermions, unveilling their Lie algebra content. (A.C.A.S.) [pt
Conformal FDTD modeling wake fields
Energy Technology Data Exchange (ETDEWEB)
Jurgens, T.; Harfoush, F.
1991-05-01
Many computer codes have been written to model wake fields. Here we describe the use of the Conformal Finite Difference Time Domain (CFDTD) method to model the wake fields generated by a rigid beam traveling through various accelerating structures. The non- cylindrical symmetry of some of the problems considered here requires the use of a three dimensional code. In traditional FDTD codes, curved surfaces are approximated by rectangular steps. The errors introduced in wake field calculations by such an approximation can be reduced by increasing the mesh size, therefore increasing the cost of computing. Another approach, validated here, deforms Ampere and Faraday contours near a media interface so as to conform to the interface. These improvements of the FDTD method result in better accuracy of the fields at asymptotically no computational cost. This method is also capable of modeling thin wires as found in beam profile monitors, and slots and cracks as found in resistive wall motions. 4 refs., 5 figs.
The generalized Erlangen program and setting a geometry for four- dimensional conformal fields
International Nuclear Information System (INIS)
Ne'eman, Y.; Texas Univ., Austin, TX; Hehl, F.W.; Mielke, E.W.
1993-01-01
This is the text of a talk at the International Symposium on ''Mathematical Physics towards the XXI Century'' held in March 1993 at Beersheva, Israel. In the first part we attempt to summarize XXth Century Physics, in the light of Kelvin's 1900 speech ''Dark Clouds over XIXth Century Physics.'' Contrary to what is usually said, Kelvin predicted that the ''clouds'' (relativity and quantum mechanics) would revolutionize physics and that one hundred years might be needed to harmonize them with classical physics. Quantum Gravity can be considered as a leftover from Kelvin's program -- so are the problems with the interpretation of quantum mechanics. At the end of the XXth Century, the Standard Model is the new panoramic synthesis, drawn in gauge-geometric lines -- realizing the Erlangen program beyond F. Klein's expectations. The hierarchy problem and the smallness of the cosmological constant are our ''clouds'', generations and the Higgs sector are to us what radioactivity was in 1900. In the second part we describe Metric-Affine spacetimes. We construct the Noether machinery and provide expressions for the conserved energy and hypermomentum. Superimposing conformal invariance over the affine structure induces the Virasoro-like infinite constraining algebra of diffeomorphisms, applied with constant parameters and opening the possibility of a 4DCFT, similar to 2DCFT
Logarithmic conformal field theory
Gainutdinov, Azat; Ridout, David; Runkel, Ingo
2013-12-01
Conformal field theory (CFT) has proven to be one of the richest and deepest subjects of modern theoretical and mathematical physics research, especially as regards statistical mechanics and string theory. It has also stimulated an enormous amount of activity in mathematics, shaping and building bridges between seemingly disparate fields through the study of vertex operator algebras, a (partial) axiomatisation of a chiral CFT. One can add to this that the successes of CFT, particularly when applied to statistical lattice models, have also served as an inspiration for mathematicians to develop entirely new fields: the Schramm-Loewner evolution and Smirnov's discrete complex analysis being notable examples. When the energy operator fails to be diagonalisable on the quantum state space, the CFT is said to be logarithmic. Consequently, a logarithmic CFT is one whose quantum space of states is constructed from a collection of representations which includes reducible but indecomposable ones. This qualifier arises because of the consequence that certain correlation functions will possess logarithmic singularities, something that contrasts with the familiar case of power law singularities. While such logarithmic singularities and reducible representations were noted by Rozansky and Saleur in their study of the U (1|1) Wess-Zumino-Witten model in 1992, the link between the non-diagonalisability of the energy operator and logarithmic singularities in correlators is usually ascribed to Gurarie's 1993 article (his paper also contains the first usage of the term 'logarithmic conformal field theory'). The class of CFTs that were under control at this time was quite small. In particular, an enormous amount of work from the statistical mechanics and string theory communities had produced a fairly detailed understanding of the (so-called) rational CFTs. However, physicists from both camps were well aware that applications from many diverse fields required significantly more
Vertex operator algebras and conformal field theory
International Nuclear Information System (INIS)
Huang, Y.Z.
1992-01-01
This paper discusses conformal field theory, an important physical theory, describing both two-dimensional critical phenomena in condensed matter physics and classical motions of strings in string theory. The study of conformal field theory will deepen the understanding of these theories and will help to understand string theory conceptually. Besides its importance in physics, the beautiful and rich mathematical structure of conformal field theory has interested many mathematicians. New relations between different branches of mathematics, such as representations of infinite-dimensional Lie algebras and Lie groups, Riemann surfaces and algebraic curves, the Monster sporadic group, modular functions and modular forms, elliptic genera and elliptic cohomology, Calabi-Yau manifolds, tensor categories, and knot theory, are revealed in the study of conformal field theory. It is therefore believed that the study of the mathematics involved in conformal field theory will ultimately lead to new mathematical structures which would be important to both mathematics and physics
Directory of Open Access Journals (Sweden)
Song-Lin Wang
2017-04-01
Full Text Available Objective: To explore the efficacy and safety of conventional radiotherapy of chest wall and clavicular field and three-dimensional conformal radiotherapy in patients after modified radical mastectomy. Methods: A total of 84 patients who were admitted in our hospital after modified radical mastectomy were included in the study and divided into the conventional radiotherapy group (n=42 and the three-dimensional conformal radiotherapy group (n=42 according to different radiotherapy methods. The patients in the conventional radiotherapy group were given conventional radiotherapy of chest wall and clavicular field, while the patients in the three-dimensional conformal radiotherapy group were given three-dimensional conformal radiotherapy. The serum tumor markers and peripheral blood T lymphocyte subsets 6-8 weeks after treatment in the two groups were detected. The clinical efficacy, and toxic and side effects in the two groups were evaluated. Results: The serum CA15-3, CA125, CEA, and CK19 levels after treatment in the two groups were significantly reduced when compared with before treatment, CD3 +,CD4 +, and CD4 +/CD8 + were significantly elevated, while CD8 + was significantly reduced when compared with before treatment, but the comparison of the above indicators between the two groups was not statistically significant. The occurrence rate of radioactive skin damage and pneumonia after treatment in the conventional radiotherapy group was significantly higher than that in the three-dimensional conformal radiotherapy group. Conclusions: The two kinds of radiotherapy schemes have an equal efficacy, but the toxic and side effects of three-dimensional conformal radiotherapy are significantly lower than those by the conventional radiotherapy, with a certain advantage.
An introduction to conformal field theory
International Nuclear Information System (INIS)
Zuber, J.B.
1995-01-01
The aim of these lectures is to present an introduction at a fairly elementary level to recent developments in two dimensional field theory, namely in conformal field theory. We shall see the importance of new structures related to infinite dimensional algebras: current algebras and Virasoro algebra. These topics will find physically relevant applications in the lectures by Shankar and Ian Affeck. (author)
Fusion rules in conformal field theory
International Nuclear Information System (INIS)
Fuchs, J.
1993-06-01
Several aspects of fusion rings and fusion rule algebras, and of their manifestations in two-dimensional (conformal) field theory, are described: diagonalization and the connection with modular invariance; the presentation in terms of quotients of polynomial rings; fusion graphs; various strategies that allow for a partial classification; and the role of the fusion rules in the conformal bootstrap programme. (orig.)
On the conformal higher spin unfolded equation for a three-dimensional self-interacting scalar field
Energy Technology Data Exchange (ETDEWEB)
Nilsson, Bengt E.W. [Fundamental Physics, Chalmers University of Technology,SE-412 96 Göteborg (Sweden)
2016-08-24
We propose field equations for the conformal higher spin system in three dimensions coupled to a conformal scalar field with a sixth order potential. Both the higher spin equation and the unfolded equation for the scalar field have source terms and are based on a conformal higher spin algebra which we treat as an expansion in multi-commutators. Explicit expressions for the source terms are suggested and subjected to some simple tests. We also discuss a cascading relation between the Chern-Simons action for the higher spin gauge theory and an action containing a term for each spin that generalizes the spin 2 Chern-Simons action in terms of the spin connection expressed in terms of the frame field. This cascading property is demonstrated in the free theory for spin 3 but should work also in the complete higher spin theory.
Herdeiro, Victor
2017-09-01
Herdeiro and Doyon [Phys. Rev. E 94, 043322 (2016), 10.1103/PhysRevE.94.043322] introduced a numerical recipe, dubbed uv sampler, offering precise estimations of the conformal field theory (CFT) data of the planar two-dimensional (2D) critical Ising model. It made use of scale invariance emerging at the critical point in order to sample finite sublattice marginals of the infinite plane Gibbs measure of the model by producing holographic boundary distributions. The main ingredient of the Markov chain Monte Carlo sampler is the invariance under dilation. This paper presents a generalization to higher dimensions with the critical 3D Ising model. This leads to numerical estimations of a subset of the CFT data—scaling weights and structure constants—through fitting of measured correlation functions. The results are shown to agree with the recent most precise estimations from numerical bootstrap methods [Kos, Poland, Simmons-Duffin, and Vichi, J. High Energy Phys. 08 (2016) 036, 10.1007/JHEP08(2016)036].
Operator algebras and conformal field theory
International Nuclear Information System (INIS)
Gabbiani, F.; Froehlich, J.
1993-01-01
We define and study two-dimensional, chiral conformal field theory by the methods of algebraic field theory. We start by characterizing the vacuum sectors of such theories and show that, under very general hypotheses, their algebras of local observables are isomorphic to the unique hyperfinite type III 1 factor. The conformal net determined by the algebras of local observables is proven to satisfy Haag duality. The representation of the Moebius group (and presumably of the entire Virasoro algebra) on the vacuum sector of a conformal field theory is uniquely determined by the Tomita-Takesaki modular operators associated with its vacuum state and its conformal net. We then develop the theory of Mebius covariant representations of a conformal net, using methods of Doplicher, Haag and Roberts. We apply our results to the representation theory of loop groups. Our analysis is motivated by the desire to find a 'background-independent' formulation of conformal field theories. (orig.)
The logarithmic conformal field theories
International Nuclear Information System (INIS)
Rahimi Tabar, M.R.; Aghamohammadi, A.; Khorrami, M.
1997-01-01
We study the correlation functions of logarithmic conformal field theories. First, assuming conformal invariance, we explicitly calculate two- and three-point functions. This calculation is done for the general case of more than one logarithmic field in a block, and more than one set of logarithmic fields. Then we show that one can regard the logarithmic field as a formal derivative of the ordinary field with respect to its conformal weight. This enables one to calculate any n-point function containing the logarithmic field in terms of ordinary n-point functions. Finally, we calculate the operator product expansion (OPE) coefficients of a logarithmic conformal field theory, and show that these can be obtained from the corresponding coefficients of ordinary conformal theory by a simple derivation. (orig.)
Naturality in conformal field theory
International Nuclear Information System (INIS)
Moore, G.; Seiberg, N.
1989-01-01
We discuss constraints on the operator product coefficients in diagonal and nondiagonal rational conformal field theories. Nondiagonal modular invariants always arise from automorphisms of the fusion rule algebra or from extensions of the chiral algebra. Moreover, when the chiral algebra has been maximally extended a strong form of the naturality principle of field theory can be proven for rational conformal field theory: operator product coefficients vanish if and only if the corresponding fusion rules vanish; that is, if and only if the vanishing can be understood in terms of a symmetry. We illustrate these ideas with several examples. We also generalize our ideas about rational conformal field theories to a larger class of theories: 'quasi-rational conformal field theories' and we explore some of their properties. (orig.)
Conformal transformation and symplectic structure of self-dual fields
International Nuclear Information System (INIS)
Yang Kongqing; Luo Yan
1996-01-01
Considered two dimensional self-dual fields, the symplectic structure on the space of solutions is given. It is shown that this structure is Poincare invariant. The Lagrangian of two dimensional self-dual field is invariant under infinite one component conformal group, then this symplectic structure is also invariant under this conformal group. The conserved currents in geometrical formalism are also obtained
Conformal invariance and two-dimensional physics
International Nuclear Information System (INIS)
Zuber, J.B.
1993-01-01
Actually, physicists and mathematicians are very interested in conformal invariance: geometric transformations which keep angles. This symmetry is very important for two-dimensional systems as phase transitions, string theory or node mathematics. In this article, the author presents the conformal invariance and explains its usefulness
Topics in low-dimensional field theory
International Nuclear Information System (INIS)
Crescimanno, M.J.
1991-01-01
Conformal field theory is a natural tool for understanding two- dimensional critical systems. This work presents results in the lagrangian approach to conformal field theory. The first sections are chiefly about a particular class of field theories called coset constructions and the last part is an exposition of the connection between two-dimensional conformal theory and a three-dimensional gauge theory whose lagrangian is the Chern-Simons density
Coadjoint orbits and conformal field theory
International Nuclear Information System (INIS)
Taylor, W. IV.
1993-08-01
This thesis is primarily a study of certain aspects of the geometric and algebraic structure of coadjoint orbit representations of infinite-dimensional Lie groups. The goal of this work is to use coadjoint orbit representations to construct conformal field theories, in a fashion analogous to the free-field constructions of conformal field theories. The new results which are presented in this thesis are as follows: First, an explicit set of formulae are derived giving an algebraic realization of coadjoint orbit representations in terms of differential operators acting on a polynomial Fock space. These representations are equivalent to dual Verma module representations. Next, intertwiners are explicitly constructed which allow the construction of resolutions for irreducible representations using these Fock space realizations. Finally, vertex operators between these irreducible representations are explicitly constructed as chain maps between the resolutions; these vertex operators allow the construction of rational conformal field theories according to an algebraic prescription
An introduction to conformal field theory
International Nuclear Information System (INIS)
Gaberdiel, Matthias R.; Fitzwilliam College, Cambridge
2000-01-01
A comprehensive introduction to two-dimensional conformal field theory is given. The structure of the meromorphic subtheory is described in detail, and a number of examples are presented explicitly. Standard constructions such as the coset and the orbifold construction are explained. The concept of a representation of the meromorphic theory is introduced, and the role of Zhu's algebra in classifying highest weight representations is elucidated. The fusion product of two representations and the corresponding fusion rules are defined, and Verlinde's formula is explained. Finally, higher correlation functions are considered, and the polynomial relations of Moore and Seiberg and the quantum group structure of chiral conformal field theory are discussed. The treatment is relatively general and also allows for a description of less well known classes of theories such as logarithmic conformal field theories. (author)
Inverse bootstrapping conformal field theories
Li, Wenliang
2018-01-01
We propose a novel approach to study conformal field theories (CFTs) in general dimensions. In the conformal bootstrap program, one usually searches for consistent CFT data that satisfy crossing symmetry. In the new method, we reverse the logic and interpret manifestly crossing-symmetric functions as generating functions of conformal data. Physical CFTs can be obtained by scanning the space of crossing-symmetric functions. By truncating the fusion rules, we are able to concentrate on the low-lying operators and derive some approximate relations for their conformal data. It turns out that the free scalar theory, the 2d minimal model CFTs, the ϕ 4 Wilson-Fisher CFT, the Lee-Yang CFTs and the Ising CFTs are consistent with the universal relations from the minimal fusion rule ϕ 1 × ϕ 1 = I + ϕ 2 + T , where ϕ 1 , ϕ 2 are scalar operators, I is the identity operator and T is the stress tensor.
Causality Constraints in Conformal Field Theory
CERN. Geneva
2015-01-01
Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d-dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂φ)4 coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinni...
Causality constraints in conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University,Ithaca, New York (United States)
2016-05-17
Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂ϕ){sup 4} coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinning operators.
International Nuclear Information System (INIS)
Carol, Mark; Grant, Walter H.; Bleier, Alan R.; Kania, Alex A.; Targovnik, Harris S.; Butler, E. Brian; Shiao, W. Woo
1996-01-01
Purpose: Intensity modulated beam systems have been developed as a means of creating a high-dose region that closely conforms to the prescribed target volume while also providing specific sparing of organs at risk within complex treatment geometries. The slice-by-slice treatment paradigm used by one such system for delivering intensity modulated fields introduces regions of dose nonuniformity where each pair of treatment slices abut. A study was designed to evaluate whether or not the magnitude of the nonuniformity that results from this segmental delivery paradigm is significant relative to the overall dose nonuniformity present in the intensity modulation technique itself. An assessment was also made as to the increase in nonuniformity that would result if errors were made in indexing during treatment delivery. Methods and Materials: Treatment plans were generated to simulate correctly indexed and incorrectly indexed treatments of 4, 10, and 18 cm diameter targets. Indexing errors of from 0.1 to 2.0 mm were studied. Treatment plans were also generated for targets of the same diameter but of lengths that did not require indexing of the treatment couch. Results: The nonuniformity that results from the intensity modulation delivery paradigm is 11-16% for targets where indexing is not required. Correct indexing of the couch adds an additional 1-2% in nonuniformity. However, a couch indexing error of as little as 1 mm can increase the total nonuniformity to as much as 25%. All increases in nonuniformity from indexing are essentially independent of target diameter. Conclusions: The dose nonuniformity introduced by the segmental strip delivery paradigm is small relative to the nonuniformity present in the intensity modulation paradigm itself. A positioning accuracy of better than 0.5 mm appears to be required when implementing segmental intensity modulated treatment plans
Topics in conformal field theory
International Nuclear Information System (INIS)
Kiritsis, E.B.
1988-01-01
In this work two major topics in Conformal Field Theory are discussed. First a detailed investigation of N = 2 Superconformal theories is presented. The structure of the representations of the N = 2 superconformal algebras is investigated and the character formulae are calculated. The general structure of N = 2 superconformal theories is elucidated and the operator algebra of the minimal models is derived. The first minimal system is discussed in more detail. Second, applications of the conformal techniques are studied in the Ashkin-Teller model. The c = 1 as well as the c = 1/2 critical lines are discussed in detail
Sekine, Ryojun; Aoki, Hiroyuki; Ito, Shinzaburo
2009-05-21
The localization and orientation of the symmetric diblock copolymer chain in a quasi-two-dimensional microphase-separated structure were studied by scanning near-field optical microscopy (SNOM). In the monolayer of poly(isobutyl methacrylate)-block-poly(octadecyl methacrylate) (PiBMA-b-PODMA), the individual PiBMA subchains were directly observed by SNOM, and the center of mass (CM) and orientational angle relative to the phase interface were examined at the single chain level. It was found that the position of the CM and the orientation of the PiBMA subchain in the lamellar structure were dependent on the curvature of the PiBMA/PODMA interface. As the interface was bent toward the objective chain, the block chain preferred the CM position closer to the domain center, and the conformation was strongly oriented perpendicularly to the domain interface. With increase of the curvature, the steric hindrance among the block chain increases, resulting in the stretched conformation.
Quantum groups and algebraic geometry in conformal field theory
International Nuclear Information System (INIS)
Smit, T.J.H.
1989-01-01
The classification of two-dimensional conformal field theories is described with algebraic geometry and group theory. This classification is necessary in a consistent formulation of a string theory. (author). 130 refs.; 4 figs.; schemes
Moduli spaces of unitary conformal field theories
International Nuclear Information System (INIS)
Wendland, K.
2000-08-01
We investigate various features of moduli spaces of unitary conformal field theories. A geometric characterization of rational toroidal conformal field theories in arbitrary dimensions is presented and discussed in relation to singular tori and those with complex multiplication. We study the moduli space M 2 of unitary two-dimensional conformal field theories with central charge c = 2. All the 26 non-exceptional non-isolated irreducible components of M 2 are constructed that may be obtained by an orbifold procedure from toroidal theories. The parameter spaces and partition functions are calculated explicitly. All multicritical points and lines are determined, such that all but three of these 26 components are directly or indirectly connected to the space of toroidal theories in M 2 . Relating our results to those by Dixon, Ginsparg, Harvey on the classification of c = 3/2 superconformal field theories, we give geometric interpretations to all non-isolated orbifolds discussed by them and correct their statements on multicritical points within the moduli space of c = 3/2 superconformal field theories. In the main part of this work, we investigate the moduli space M of N = (4, 4) superconformal field theories with central charge c = 6. After a slight emendation of its global description we give generic partition functions for models contained in M. We explicitly determine the locations of various known models in the component of M associated to K3 surfaces
Arithmetics, geometry and conformal fields
Itzykson, Claude
1992-03-17
The last few years have witnessed a remarkeble conjunction of methods in such diverse domains as strings and topological field theory, two dimensional statistical physics, classical and quantum integrable systems. The lectures will aim to present some of the underlying mathematics at an elementary and pedagogical level, for their intrinsic value.
Introduction to twisted conformal fields
International Nuclear Information System (INIS)
Kazama, Y.
1988-01-01
A pedagogical account is given of the recent developments in the theory of twisted conformal fields. Among other things, the main part of the lecture concerns the construction of the twist-emission vertex operator, which is a generalization of the fermion emission vertex in the superstring theory. Several different forms of the vertex are derived and their mutural relationships are clarified. In this paper, the authors include a brief survey of the history of the fermion emission vertex, as it offers a good perspective in which to appreciate the logical development
Strings, conformal fields and topology
International Nuclear Information System (INIS)
Kaku, Michio
1991-01-01
String Theory has advanced at an astonishing pace in the last few years, and this book aims to acquaint the reader with the most active topics of research in the field. Building on the foundations laid in his Introduction to Superstrings, Professor Kaku discusses such topics as the classification of conformal string theories, knot theory, the Yang-Baxter relation, quantum groups, the non-polynominal closed string field theory, matrix models, and topological field theory. Several chapters review the fundamentals of string theory, making the presentation of the material self-contained while keeping overlap with the earlier book to a minimum. The book conveys the vitality of current research in string theory and places readers at its forefront. (orig.) With 40 figs. in 50 parts
Conformal Transformations and Conformal Killing Fields
Definition 1.1 A semi-Riemannian manifold is a pair (M,g) consisting of a differentiate (i.e. C∞) manifold M and a differentiable tensor field g which assigns to each point a ∈ M a non-degenerate and symmetric bilinear form on the tangent space TaM: g_a :T_a M × T_a M to R.
Logarithmic conformal field theory through nilpotent conformal dimensions
International Nuclear Information System (INIS)
Moghimi-Araghi, S.; Rouhani, S.; Saadat, M.
2001-01-01
We study logarithmic conformal field theories (LCFTs) through the introduction of nilpotent conformal weights. Using this device, we derive the properties of LCFTs such as the transformation laws, singular vectors and the structure of correlation functions. We discuss the emergence of an extra energy momentum tensor, which is the logarithmic partner of the energy momentum tensor
Families and degenerations of conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Roggenkamp, D.
2004-09-01
In this work, moduli spaces of conformal field theories are investigated. In the first part, moduli spaces corresponding to current-current deformation of conformal field theories are constructed explicitly. For WZW models, they are described in detail, and sigma model realizations of the deformed WZW models are presented. The second part is devoted to the study of boundaries of moduli spaces of conformal field theories. For this purpose a notion of convergence of families of conformal field theories is introduced, which admits certain degenerated conformal field theories to occur as limits. To such a degeneration of conformal field theories, a degeneration of metric spaces together with additional geometric structures can be associated, which give rise to a geometric interpretation. Boundaries of moduli spaces of toroidal conformal field theories, orbifolds thereof and WZW models are analyzed. Furthermore, also the limit of the discrete family of Virasoro minimal models is investigated. (orig.)
Conformal invariance in the quantum field theory
International Nuclear Information System (INIS)
Kurak, V.
1975-09-01
Basic features concerning the present knowledge of conformal symmetry are illustrated in a simple model. Composite field dimensions of this model are computed and related to the conformal group. (author) [pt
Conformal field theory with two kinds of Bosonic fields and two linear dilatons
International Nuclear Information System (INIS)
Kamani, Davoud
2010-01-01
We consider a two-dimensional conformal field theory which contains two kinds of the bosonic degrees of freedom. Two linear dilaton fields enable to study a more general case. Various properties of the model such as OPEs, central charge, conformal properties of the fields and associated algebras will be studied. (author)
New unified field theory based on the conformal group
Energy Technology Data Exchange (ETDEWEB)
Pessa, E [Rome Univ. (Italy). Ist. di Matematica
1980-10-01
Based on a six-dimensional generalization of Maxwell's equations, a new unified theory of the electromagnetic and gravitational field is developed. Additional space-time coordinates are interpreted only as mathematical tools in order to obtain a linear realization of the four-dimensional conformal group.
Lagrangian model of conformal invariant interacting quantum field theory
International Nuclear Information System (INIS)
Lukierski, J.
1976-01-01
A Lagrangian model of conformal invariant interacting quantum field theory is presented. The interacting Lagrangian and free Lagrangian are derived replacing the canonical field phi by the field operator PHIsub(d)sup(c) and introducing the conformal-invariant interaction Lagrangian. It is suggested that in the conformal-invariant QFT with the dimensionality αsub(B) obtained from the bootstrep equation, the normalization constant c of the propagator and the coupling parametery do not necessarily need to satisfy the relation xsub(B) = phi 2 c 3
Conformal invariant quantum field theory and composite field operators
International Nuclear Information System (INIS)
Kurak, V.
1976-01-01
The present status of conformal invariance in quantum field theory is reviewed from a non group theoretical point of view. Composite field operators dimensions are computed in some simple models and related to conformal symmetry
Conformal and Lie superalgebras motivated from free fermionic fields
International Nuclear Information System (INIS)
Ma, Shukchuen
2003-01-01
In this paper, we construct six families of conformal superalgebras of infinite type, motivated from free quadratic fermonic fields with derivatives, and we prove their simplicity. The Lie superalgebras generated by these conformal superalgebras are proven to be simple except for a few special cases in the general linear superalgebras and the type-Q lie superalgebras, in which these Lie superalgebras have a one-dimensional centre and the quotient Lie superalgebras modulo the centre are simple. Certain natural central extensions of these families of conformal superalgebras are also given. Moreover, we prove that these conformal superalgebras are generated by their finite-dimensional subspaces of minimal weight in a certain sense. It is shown that a conformal superalgebra is simple if and only if its generated Lie superalgebra does not contain a proper nontrivial ideal with a one-variable structure
Conformal field theory and 2D critical phenomena. Part 1
International Nuclear Information System (INIS)
Zamolodchikov, A.B.; Zamolodchikov, Al.B.
1989-01-01
Review of the recent developments in the two-dimensional conformal field theory and especially its applications to the physics of 2D critical phenomena is given. It includes the Ising model, the Potts model. Minimal models, corresponding to theories invariant under higher symmetries, such as superconformal theories, parafermionic theories and theories with current and W-algebras are also discussed. Non-hamiltonian approach to two-dimensional field theory is formulated. 126 refs
Quantum Conformal Algebras and Closed Conformal Field Theory
Anselmi, D
1999-01-01
We investigate the quantum conformal algebras of N=2 and N=1 supersymmetric gauge theories. Phenomena occurring at strong coupling are analysed using the Nachtmann theorem and very general, model-independent, arguments. The results lead us to introduce a novel class of conformal field theories, identified by a closed quantum conformal algebra. We conjecture that they are the exact solution to the strongly coupled large-N_c limit of the open conformal field theories. We study the basic properties of closed conformal field theory and work out the operator product expansion of the conserved current multiplet T. The OPE structure is uniquely determined by two central charges, c and a. The multiplet T does not contain just the stress-tensor, but also R-currents and finite mass operators. For this reason, the ratio c/a is different from 1. On the other hand, an open algebra contains an infinite tower of non-conserved currents, organized in pairs and singlets with respect to renormalization mixing. T mixes with a se...
Riemann monodromy problem and conformal field theories
International Nuclear Information System (INIS)
Blok, B.
1989-01-01
A systematic analysis of the use of the Riemann monodromy problem for determining correlators (conformal blocks) on the sphere is presented. The monodromy data is constructed in terms of the braid matrices and gives a constraint on the noninteger part of the conformal dimensions of the primary fields. To determine the conformal blocks we need to know the order of singularities. We establish a criterion which tells us when the knowledge of the conformal dimensions of primary fields suffice to determine the blocks. When zero modes of the extended algebra are present the analysis is more difficult. In this case we give a conjecture that works for the SU(2) WZW case. (orig.)
Defects in conformal field theory
International Nuclear Information System (INIS)
Billò, Marco; Gonçalves, Vasco; Lauria, Edoardo; Meineri, Marco
2016-01-01
We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.
Defects in conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Billò, Marco [Dipartimento di Fisica, Università di Torino, and Istituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Gonçalves, Vasco [Centro de Física do Porto,Departamento de Física e Astronomia Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); ICTP South American Institute for Fundamental Research Instituto de Física Teórica,UNESP - University Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Lauria, Edoardo [Institute for Theoretical Physics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Meineri, Marco [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Scuola Normale Superiore, and Istituto Nazionale di Fisica Nucleare - sezione di Pisa,Piazza dei Cavalieri 7 I-56126 Pisa (Italy)
2016-04-15
We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.
Analytic aspects of rational conformal field theories
International Nuclear Information System (INIS)
Kiritsis, E.B.; Lawrence Berkeley Lab., CA
1990-01-01
The problem of deriving linear differential equations for correlation functions of Rational Conformal Field Theories is considered. Techniques from the theory of fuchsian differential equations are used to show that knowledge of the central charge, dimensions of primary fields and fusion rules are enough to fix the differential equations for one- and two-point functions on the tours. Any other correlation function can be calculated along similar lines. The results settle the issue of 'exact solution' of rational conformal field theories. (orig.)
Conformal three dimensional radiotherapy treatment planning in Lund
Energy Technology Data Exchange (ETDEWEB)
Knoos, T; Nilsson, P [Lund Univ. (Sweden). Dept. of Radiation Physics; Anders, A [Lund Univ. (Sweden). Dept. of Oncology
1995-12-01
The use of conformal therapy is based on 3-dimensional treatment planning as well as on methods and routines for 3-dimensional patient mapping, 3-dimensional virtual simulation and others. The management of patients at the Radiotherapy Department at the University Hospital in Lund (Sweden) is discussed. About 2100 new patients are annually treated with external radiotherapy using seven linear accelerators. Three of the accelerators have dual photon energies and electron treatment facilities. A multi-leaf collimator as well as an electronic portal imaging device are available on one machine. Two simulators and an in-house CT-scanner are used for treatment planning. From 1988 to 1992 Scandiplan (Umplan) was used. Since 1992, the treatment planning system is TMS (HELAX AB, Sweden), which is based on the pencil beam algorithm of Ahnesjo. The calculations use patient modulated accelerator specific energy fluence spectra which are compiled with pencil beams from Monte Carlo generated energy absorption kernels. Heterogeneity corrections are performed with results close to conventional algorithms. Irregular fields, either from standard or individual blocks and from multi-leaf collimators are handled by the treatment planning system. The field shape is determined conveniently using the beam`s eye view. The final field shape is exported electronically to either the block cutting machine or the multileaf collimator control computer. All patient fields are checked against the beam`s eye view during simulation using manual methods. Treatment verification is performed by portal films and in vivo dosimetry with silicon diodes or TL-dosimetry. Up to now, approximately 4400 patients have received a highly individualized 3-dimensional conformal treatment.
Conformal three dimensional radiotherapy treatment planning in Lund
International Nuclear Information System (INIS)
Knoos, T.; Nilsson, P.; Anders, A.
1995-01-01
The use of conformal therapy is based on 3-dimensional treatment planning as well as on methods and routines for 3-dimensional patient mapping, 3-dimensional virtual simulation and others. The management of patients at the Radiotherapy Department at the University Hospital in Lund (Sweden) is discussed. About 2100 new patients are annually treated with external radiotherapy using seven linear accelerators. Three of the accelerators have dual photon energies and electron treatment facilities. A multi-leaf collimator as well as an electronic portal imaging device are available on one machine. Two simulators and an in-house CT-scanner are used for treatment planning. From 1988 to 1992 Scandiplan (Umplan) was used. Since 1992, the treatment planning system is TMS (HELAX AB, Sweden), which is based on the pencil beam algorithm of Ahnesjo. The calculations use patient modulated accelerator specific energy fluence spectra which are compiled with pencil beams from Monte Carlo generated energy absorption kernels. Heterogeneity corrections are performed with results close to conventional algorithms. Irregular fields, either from standard or individual blocks and from multi-leaf collimators are handled by the treatment planning system. The field shape is determined conveniently using the beam's eye view. The final field shape is exported electronically to either the block cutting machine or the multileaf collimator control computer. All patient fields are checked against the beam's eye view during simulation using manual methods. Treatment verification is performed by portal films and in vivo dosimetry with silicon diodes or TL-dosimetry. Up to now, approximately 4400 patients have received a highly individualized 3-dimensional conformal treatment
Quantum Hamiltonian reduction and conformal field theories
International Nuclear Information System (INIS)
Bershadsky, M.
1991-01-01
It is proved that irreducible representation of the Virasoro algebra can be extracted from an irreducible representation space of the SL (2, R) current algebra by putting a constraint on the latter using the BRST formalism. Thus there is a SL(2, R) symmetry in the Virasoro algebra which is gauged and hidden. This construction of the Virasoro algebra is the quantum analog of the Hamiltonian reduction. The author then naturally leads to consider an SL(2, R) Wess-Zumino-Witten model. This system is related to the quantum field theory of the coadjoint orbit of the Virasoro group. Based on this result he presents the canonical derivation of the SL(2, R) current algebra in Polyakov's theory of two dimensional gravity; it is manifestation of the SL(2, R) symmetry in the conformal field theory hidden by the quantum Hamiltonian reduction. He discusses the quantum Hamiltonian reduction of the SL(n, R) current algebra for the general type of constraints labeled by index 1 ≤ l ≤ (n - 1) and claim that it leads to the new extended conformal algebras W n l . For l = 1 he recovers the well known W n algebra introduced by A. Zamolodchikov. For SL(3, R) Wess-Zumino-Witten model there are two different possibilities of constraining it. The first possibility gives the W 3 algebra, while the second leads to the new chiral algebra W 3 2 generated by the stress-energy tensor, two bosonic supercurrents with spins 3/2 and the U(1) current. He conjectures a Kac formula that describes the highly reducible representation for this algebra. He also makes some speculations concerning the structure of W gravity
International Nuclear Information System (INIS)
Degiovanni, P.
1990-01-01
We compute the modular properties of the possible genus-one characters of some Rational Conformal Field Theories starting from their fusion rules. We show that the possible choices of S matrices are indexed by some automorphisms of the fusion algebra. We also classify the modular invariant partition functions of these theories. This gives the complete list of modular invariant partition functions of Rational Conformal Field Theories with respect to the A N (1) level one algebra. (orig.)
Towards the classification of conformal field theories in arbitrary dimension
Anselmi, D
2000-01-01
I identify the subclass of higher-dimensional conformal field theories that is most similar to two-dimensional conformal field theory. In this subclass the domain of validity of the recently proposed formula for the irreversibility of the renormalization-group flow is suitably enhanced. The trace anomaly is quadratic in the Ricci tensor and contains a unique central charge. This implies, in particular, a relationship between the coefficient in front of the Euler density (charge a) and the stress-tensor two-point function (charge c). I check the prediction in detail in four, six and eight dimensions, and then in arbitrary dimension. In four and six dimensions there is agreement with results from the AdS/CFT correspondence. A by-product is a mathematical algorithm to construct conformal invariants.
Conformal invariance in quantum field theory
International Nuclear Information System (INIS)
Grensing, G.
1978-01-01
We study the transformation law of interacting fields under the universal covering group of the conformal group. It is defined with respect to the representations of the discrete series. These representations are field representations in the sense that they act on finite component fields defined over Minkowski space. The conflict with Einstein causality is avoided as in the case of free fields with canonical dimension. Furthermore, we determine the conformal invariant two-point function of arbitrary spin. Our result coincides with that obtained by Ruehl. In particular, we investigate the two-point function of symmetric and traceless tensor fields and give the explicit form of the trace terms
Conformal field theories and tensor categories. Proceedings
Energy Technology Data Exchange (ETDEWEB)
Bai, Chengming [Nankai Univ., Tianjin (China). Chern Institute of Mathematics; Fuchs, Juergen [Karlstad Univ. (Sweden). Theoretical Physics; Huang, Yi-Zhi [Rutgers Univ., Piscataway, NJ (United States). Dept. of Mathematics; Kong, Liang [Tsinghua Univ., Beijing (China). Inst. for Advanced Study; Runkel, Ingo; Schweigert, Christoph (eds.) [Hamburg Univ. (Germany). Dept. of Mathematics
2014-08-01
First book devoted completely to the mathematics of conformal field theories, tensor categories and their applications. Contributors include both mathematicians and physicists. Some long expository articles are especially suitable for beginners. The present volume is a collection of seven papers that are either based on the talks presented at the workshop ''Conformal field theories and tensor categories'' held June 13 to June 17, 2011 at the Beijing International Center for Mathematical Research, Peking University, or are extensions of the material presented in the talks at the workshop. These papers present new developments beyond rational conformal field theories and modular tensor categories and new applications in mathematics and physics. The topics covered include tensor categories from representation categories of Hopf algebras, applications of conformal field theories and tensor categories to topological phases and gapped systems, logarithmic conformal field theories and the corresponding non-semisimple tensor categories, and new developments in the representation theory of vertex operator algebras. Some of the papers contain detailed introductory material that is helpful for graduate students and researchers looking for an introduction to these research directions. The papers also discuss exciting recent developments in the area of conformal field theories, tensor categories and their applications and will be extremely useful for researchers working in these areas.
Conformal field theories and tensor categories. Proceedings
International Nuclear Information System (INIS)
Bai, Chengming; Fuchs, Juergen; Huang, Yi-Zhi; Kong, Liang; Runkel, Ingo; Schweigert, Christoph
2014-01-01
First book devoted completely to the mathematics of conformal field theories, tensor categories and their applications. Contributors include both mathematicians and physicists. Some long expository articles are especially suitable for beginners. The present volume is a collection of seven papers that are either based on the talks presented at the workshop ''Conformal field theories and tensor categories'' held June 13 to June 17, 2011 at the Beijing International Center for Mathematical Research, Peking University, or are extensions of the material presented in the talks at the workshop. These papers present new developments beyond rational conformal field theories and modular tensor categories and new applications in mathematics and physics. The topics covered include tensor categories from representation categories of Hopf algebras, applications of conformal field theories and tensor categories to topological phases and gapped systems, logarithmic conformal field theories and the corresponding non-semisimple tensor categories, and new developments in the representation theory of vertex operator algebras. Some of the papers contain detailed introductory material that is helpful for graduate students and researchers looking for an introduction to these research directions. The papers also discuss exciting recent developments in the area of conformal field theories, tensor categories and their applications and will be extremely useful for researchers working in these areas.
Conformal field theories, Coulomb gas picture and integrable models
International Nuclear Information System (INIS)
Zuber, J.B.
1988-01-01
The aim of the study is to present the links between some results of conformal field theory, the conventional Coulomb gas picture in statistical mechanics and the approach of integrable models. It is shown that families of conformal theories, related by the coset construction to the SU(2) Kac-Moody algebra, may be regarded as obtained from some free field, and modified by the coupling of its winding numbers to floating charges. This representation reflects the procedure of restriction of the corresponding integrable lattice models. The work may be generalized to models based on the coset construction with higher rank algebras. The corresponding integrable models are identified. In the conformal field description, generalized parafermions appear, and are coupled to free fields living on a higher-dimensional torus. The analysis is not as exhaustive as in the SU(2) case: all the various restrictions have not been identified, nor the modular invariants completely classified
Conformal symmetry in two-dimensional space: recursion representation of conformal block
International Nuclear Information System (INIS)
Zamolodchikov, A.B.
1988-01-01
The four-point conformal block plays an important part in the analysis of the conformally invariant operator algebra in two-dimensional space. The behavior of the conformal block is calculated in the present paper in the limit in which the dimension Δ of the intermediate operator tends to infinity. This makes it possible to construct a recursion relation for this function that connects the conformal block at arbitrary Δ to the blocks corresponding to the dimensions of the zero vectors in the degenerate representations of the Virasoro algebra. The relation is convenient for calculating the expansion of the conformal block in powers of the uniformizing parameters q = i π tau
Dilogarithm identities in conformal field theory
International Nuclear Information System (INIS)
Nahm, W.; Recknagel, A.; Terhoeven, M.
1992-11-01
Dilogarithm identities for the central charges and conformal dimensions exist for at least large classes of rational conformally invariant quantum field theories in two dimensions. In many cases, proofs are not yet known but the numerical and structural evidence is convincing. In particular, close relations exist to fusion rules and partition identities. We describe some examples and ideas, and present conjectures useful for the classification of conformal theories. The mathematical structures seem to be dual to Thurston's program for the classification of 3-manifolds. (orig.)
Representation theory of current algebra and conformal field theory on Riemann surfaces
International Nuclear Information System (INIS)
Yamada, Yasuhiko
1989-01-01
We study conformal field theories with current algebra (WZW-model) on general Riemann surfaces based on the integrable representation theory of current algebra. The space of chiral conformal blocks defined as solutions of current and conformal Ward identities is shown to be finite dimensional and satisfies the factorization properties. (author)
Conformal quantum field theory: From Haag-Kastler nets to Wightman fields
International Nuclear Information System (INIS)
Joerss, M.
1996-07-01
Starting from a chiral conformal Haag-Kastler net of local observables on two-dimensional Minkowski space-time, we construct associated pointlike localizable charged fields which intertwine between the superselection sectors with finite statistics of the theory. This amounts to a proof of the spin-statistics theorem, the PCT theorem, the Bisognano-Wichmann identification of modular operators, Haag duality in the vacuum sector, and the existence of operator product expansions. Our method consists of the explicit use of the representation theory of the universal covering group of SL(2,R). A central role is played by a ''conformal cluster theorem'' for conformal two-point functions in algebraic quantum field theory. Generalizing this ''conformal cluster theorem'' to the n-point functions of Haag-Kastler theories, we can finally construct from a chiral conformal net of algebras a compelte set of conformal n-point functions fulfilling the Wightman axioms. (orig.)
Quantum Yang-Mills theory of Riemann surfaces and conformal field theory
International Nuclear Information System (INIS)
Killingback, T.P.
1989-01-01
It is shown that Yang-Mills theory on a smooth surface, when suitably quantized, is a topological quantum field theory. This topological gauge theory is intimately related to two-dimensional conformal field theory. It is conjectured that all conformal field theories may be obtained from Yang-Mills theory on smooth surfaces. (orig.)
Nilpotent weights in conformal field theory
Directory of Open Access Journals (Sweden)
S. Rouhani
2001-12-01
Full Text Available Logarithmic conformal field theory can be obtained using nilpotent weights. Using such scale transformations various properties of the theory were derived. The derivation of four point function needs a knowledge of singular vectors which is derived by including nilpotent variables into the Kac determinant. This leads to inhomogeneous hypergeometric functions. Finally we consider the theory near a boundary and also introduce the concept of superfields where a multiplet of conformal fields are dealt with together. This leads to the OPE of superfields and a logarithmic partner for the energy momentum tensor.
Recent progress in irrational conformal field theory
International Nuclear Information System (INIS)
Halpern, M.B.
1993-09-01
In this talk, I will review the foundations of irrational conformal field theory (ICFT), which includes rational conformal field theory as a small subspace. Highlights of the review include the Virasoro master equation, the Ward identities for the correlators of ICFT and solutions of the Ward identities. In particular, I will discuss the solutions for the correlators of the g/h coset construction and the correlators of the affine-Sugawara nests on g contains h 1 contains hor-ellipsis contains h n . Finally, I will discuss the recent global solution for the correlators of all the ICFT's in the master equation
Remarks on Multi-Dimensional Conformal Mechanics
Directory of Open Access Journals (Sweden)
Cestmír Burdík
2009-01-01
Full Text Available Recently, Galajinsky, Lechtenfeld and Polovnikov proposed an elegant group-theoretical transformation of the generic conformal-invariant mechanics to the free one. Considering the classical counterpart of this transformation, we relate this transformation with the Weil model of Lobachewsky space.
Conformal anomalies and the Einstein field equations
Energy Technology Data Exchange (ETDEWEB)
Godazgar, Hadi [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), Mühlenberg 1, D-14476 Potsdam (Germany); Meissner, Krzysztof A. [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Nicolai, Hermann [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), Mühlenberg 1, D-14476 Potsdam (Germany)
2017-04-28
We compute corrections to the Einstein field equations which are induced by the anomalous effective actions associated to the type A conformal anomaly, both for the (non-local) Riegert action, as well as for the local action with dilaton. In all cases considered we find that these corrections can be very large.
Holographic applications of logarithmic conformal field theories
Grumiller, D.; Riedler, W.; Rosseel, J.; Zojer, T.
2013-01-01
We review the relations between Jordan cells in various branches of physics, ranging from quantum mechanics to massive gravity theories. Our main focus is on holographic correspondences between critically tuned gravity theories in anti-de Sitter space and logarithmic conformal field theories in
The solutions of affine and conformal affine Toda field theory
International Nuclear Information System (INIS)
Papadopoulos, G.; Spence, B.
1994-02-01
We give new formulations of the solutions of the field equations of the affine Toda and conformal affine Toda theories on a cylinder and two-dimensional Minkowski space-time. These solutions are parameterised in terms of initial data and the resulting covariant phase spaces are diffeomorphic to the Hamiltonian ones. We derive the fundamental Poisson brackets of the parameters of the solutions and give the general static solutions for the affine theory. (authors). 10 refs
Group of local biholomorphisms of C/sup 1/ and conformal field theory on the operator formalism
Energy Technology Data Exchange (ETDEWEB)
Budzynski, R.J.; Klimek, S.; Sadowski, P.
1989-01-01
Motivated by the operator formulation of conformal field theory on Riemann surfaces, we study the properties of the infinite dimensional group of local biholomorphic transformations (conformal reparametrizations) of C/sup 1/ and develop elements of its representation theory.
Asymptotic mass degeneracies in conformal field theories
International Nuclear Information System (INIS)
Kani, I.; Vafa, C.
1990-01-01
By applying a method of Hardy and Ramanujan to characters of rational conformal field theories, we find an asymptotic expansion for degeneracy of states in the limit of large mass which is exact for strings propagating in more than two uncompactified space-time dimensions. Moreover we explore how the rationality of the conformal theory is reflected in the degeneracy of states. We also consider the one loop partition function for strings, restricted to physical states, for arbitrary (irrational) conformal theories, and obtain an asymptotic expansion for it in the limit that the torus degenerates. This expansion depends only on the spectrum of (physical and unphysical) relevant operators in the theory. We see how rationality is consistent with the smoothness of mass degeneracies as a function of moduli. (orig.)
One loop partition function of six dimensional conformal gravity using heat kernel on AdS
Energy Technology Data Exchange (ETDEWEB)
Lovreković, Iva [Institute for Theoretical Physics, Technische Universität Wien,Wiedner Hauptstrasse 8-10/136, A-1040 Vienna (Austria)
2016-10-13
We compute the heat kernel for the Laplacians of symmetric transverse traceless fields of arbitrary spin on the AdS background in even number of dimensions using the group theoretic approach introduced in http://dx.doi.org/10.1007/JHEP11(2011)010 and apply it on the partition function of six dimensional conformal gravity. The obtained partition function consists of the Einstein gravity, conformal ghost and two modes that contain mass.
2D conformal field theories and holography
International Nuclear Information System (INIS)
Freidel, Laurent; Krasnov, Kirill
2004-01-01
It is known that the chiral part of any 2D conformal field theory defines a 3D topological quantum field theory: quantum states of this TQFT are the CFT conformal blocks. The main aim of this paper is to show that a similar CFT/TQFT relation exists also for the full CFT. The 3D topological theory that arises is a certain 'square' of the chiral TQFT. Such topological theories were studied by Turaev and Viro; they are related to 3D gravity. We establish an operator/state correspondence in which operators in the chiral TQFT correspond to states in the Turaev-Viro theory. We use this correspondence to interpret CFT correlation functions as particular quantum states of the Turaev-Viro theory. We compute the components of these states in the basis in the Turaev-Viro Hilbert space given by colored 3-valent graphs. The formula we obtain is a generalization of the Verlinde formula. The later is obtained from our expression for a zero colored graph. Our results give an interesting 'holographic' perspective on conformal field theories in two dimensions
Conformal algebras of two-dimensional disordered systems
International Nuclear Information System (INIS)
Gurarie, Victor; Ludwig, Andreas W.W.
2002-01-01
We discuss the structure of two-dimensional conformal field theories at a central charge c=0 describing critical disordered systems, polymers and percolation. We construct a novel extension of the c=0 Virasoro algebra, characterized by a number b measuring the effective number of massless degrees of freedom, and by a logarithmic partner of the stress tensor. It is argued to be present at a generic random critical point, lacking super Kac-Moody, or other higher symmetries, and is a tool to describe and classify such theories. Interestingly, this algebra is not only consistent with, but indeed naturally accommodates in general an underlying global supersymmetry. Polymers and percolation realize this algebra. Unexpectedly, we find that the c=0 Kac table of the degenerate fields contains two distinct theories with b=5/6 and b=-5/8 which we conjecture to correspond to percolation and polymers, respectively. A given Kac-table field can be degenerate only in one of them. Remarkably, we also find this algebra, and thereby an ensuing hidden supersymmetry, realized at general replica-averaged critical points, for which we derive an explicit formula for b. (author). Letter-to-the-editor
Comments on conformal Killing vector fields and quantum field theory
International Nuclear Information System (INIS)
Brown, M.R.; Ottewill, A.C.; Siklos, S.T.C.
1982-01-01
We give a comprehensive analysis of those vacuums for flat and conformally flat space-times which can be defined by timelike, hypersurface-orthogonal, conformal Killing vector fields. We obtain formulas for the difference in stress-energy density between any two such states and display the correspondence with the renormalized stress tensors. A brief discussion is given of the relevance of these results to quantum-mechanical measurements made by noninertial observers moving through flat space
International Nuclear Information System (INIS)
Ruben, Jeremy D.; Smith, Ryan; Lancaster, Craig M.; Haynes, Matthew; Jones, Phillip; Panettieri, Vanessa
2014-01-01
Purpose: To characterize and compare the components of out-of-field dose for 18-MV intensity modulated radiation therapy (IMRT) versus 3-dimensional conformal radiation therapy (3D-CRT) and their 6-MV counterparts and consider implications for second cancer induction. Methods and Materials: Comparable plans for each technique/energy were delivered to a water phantom with a sloping wall; under full scatter conditions; with field edge abutting but outside the bath to prevent internal/phantom scatter; and with shielding below the linear accelerator head to attenuate head leakage. Neutron measurements were obtained from published studies. Results: Eighteen-megavolt IMRT produces 1.7 times more out-of-field scatter than 18-MV 3D-CRT. In absolute terms, however, differences are just approximately 0.1% of central axis dose. Eighteen-megavolt IMRT reduces internal/patient scatter by 13%, but collimator scatter (C) is 2.6 times greater than 18-MV 3D-CRT. Head leakage (L) is minimal. Increased out-of-field photon scatter from 18-MV IMRT carries out-of-field second cancer risks of approximately 0.2% over and above the 0.4% from 18-MV 3D-CRT. Greater photoneutron dose from 18-MV IMRT may result in further maximal, absolute increased risk to peripheral tissue of approximately 1.2% over 18-MV 3D-CRT. Out-of-field photon scatter remains comparable for the same modality irrespective of beam energy. Machine scatter (C+L) from 18 versus 6 MV is 1.2 times higher for IMRT and 1.8 times for 3D-CRT. It is 4 times higher for 6-MV IMRT versus 3D-CRT. Reduction in internal scatter with 18 MV versus 6 MV is 27% for 3D-CRT and 29% for IMRT. Compared with 6-MV 3D-CRT, 18-MV IMRT increases out-of-field second cancer risk by 0.2% from photons and adds 0.28-2.2% from neutrons. Conclusions: Out-of-field photon dose seems to be independent of beam energy for both techniques. Eighteen-megavolt IMRT increases out-of-field scatter 1.7-fold over 3D-CRT because of greater collimator scatter despite
Logarithmic conformal field theory: beyond an introduction
International Nuclear Information System (INIS)
Creutzig, Thomas; Ridout, David
2013-01-01
This article aims to review a selection of central topics and examples in logarithmic conformal field theory. It begins with the remarkable observation of Cardy that the horizontal crossing probability of critical percolation may be computed analytically within the formalism of boundary conformal field theory. Cardy’s derivation relies on certain implicit assumptions which are shown to lead inexorably to indecomposable modules and logarithmic singularities in correlators. For this, a short introduction to the fusion algorithm of Nahm, Gaberdiel and Kausch is provided. While the percolation logarithmic conformal field theory is still not completely understood, there are several examples for which the formalism familiar from rational conformal field theory, including bulk partition functions, correlation functions, modular transformations, fusion rules and the Verlinde formula, has been successfully generalized. This is illustrated for three examples: the singlet model M(1,2), related to the triplet model W(1,2), symplectic fermions and the fermionic bc ghost system; the fractional level Wess–Zumino–Witten model based on sl-hat (2) at k=−(1/2), related to the bosonic βγ ghost system; and the Wess–Zumino–Witten model for the Lie supergroup GL(1∣1), related to SL(2∣1) at k=−(1/2) and 1, the Bershadsky–Polyakov algebra W 3 (2) and the Feigin–Semikhatov algebras W n (2) . These examples have been chosen because they represent the most accessible, and most useful, members of the three best-understood families of logarithmic conformal field theories. The logarithmic minimal models W(q,p), the fractional level Wess–Zumino–Witten models, and the Wess–Zumino–Witten models on Lie supergroups (excluding OSP(1∣2n)). In this review, the emphasis lies on the representation theory of the underlying chiral algebra and the modular data pertaining to the characters of the representations. Each of the archetypal logarithmic conformal field theories is
Boundary conditions in rational conformal field theories
International Nuclear Information System (INIS)
Behrend, Roger E.; Pearce, Paul A.; Petkova, Valentina B.; Zuber, Jean-Bernard
2000-01-01
We develop further the theory of Rational Conformal Field Theories (RCFTs) on a cylinder with specified boundary conditions emphasizing the role of a triplet of algebras: the Verlinde, graph fusion and Pasquier algebras. We show that solving Cardy's equation, expressing consistency of a RCFT on a cylinder, is equivalent to finding integer valued matrix representations of the Verlinde algebra. These matrices allow us to naturally associate a graph G to each RCFT such that the conformal boundary conditions are labelled by the nodes of G. This approach is carried to completion for sl(2) theories leading to complete sets of conformal boundary conditions, their associated cylinder partition functions and the A-D-E classification. We also review the current status for WZW sl(3) theories. Finally, a systematic generalisation of the formalism of Cardy-Lewellen is developed to allow for multiplicities arising from more general representations of the Verlinde algebra. We obtain information on the bulk-boundary coefficients and reproduce the relevant algebraic structures from the sewing constraints
Conformal FDTD modeling of 3-D wake fields
International Nuclear Information System (INIS)
Jurgens, T.G.; Harfoush, F.A.
1991-01-01
Many computer codes have been written to model wake fields. Here the authors describe the use of the Conformal Finite Difference Time Domain (CFDTD) method to model the wake fields generated by a rigid beam traveling through various accelerating structures. The non-cylindrical symmetry of some of the problems considered here requires the use of a three dimensional code. In traditional FDTD codes, curved surfaces are approximated by rectangular steps. The errors introduced in wake field calculations by such an approximation can be reduced by increasing the mesh size, therefore increasing the cost of computing. Another approach, validated here, deforms Ampere and Faraday contours near a media interface so as to conform to the interface. These improvements so as to conform to the interface. These improvements to the FDTD method result in better accuracy of the fields at asymptotically no computational cost. This method is also capable of modeling thin wires as found in beam profile monitors, and slots and cracks as found in resistive wall monitors
Introductory lectures on Conformal Field Theory and Strings
International Nuclear Information System (INIS)
Randjbar-Daemi, S.; Strathdee, J.
1990-01-01
The aim of these lectures is to provide an introduction to a first quantized formulation of string theory. This amounts to developing a consistent set of prescriptions for the perturbative computation of on-shell string amplitudes. The principal tool in this development is 2-dimensional conformal field theory on oriented manifolds of finite genus without boundaries (we treat only closed strings). This class of theory is much simpler than 4-dimensional quantum gravity with which it has many similarities. The geometry is not dynamical in this case, and the matter fields are not sensitive to local features of the geometry but only to global properties which can be characterized by a finite set of parameters (moduli). This can be formulated as field theory on a Riemann surface. We specialize mainly to free field theories for which the quantization problem can be completely solved by elementary means. An introduction to the general case will be given in Lectures II and III where the algebraic approach is discussed. The mathematics of Riemann surfaces is a well developed subject whose formalism is reviewed along with some of the principal theorems in Lecture IV. Physical string states are realized in the Hilbert space of a conformal field theory by the action of so-called ''vertex operators'' on the field theory vacuum state. Correlation functions of these vertex operators serve as ingredients for the computation of string amplitudes. They are to be integrated so as to include the contributions of all conformally inequivalent geometries, and a further manipulation (the GSO projection) is to be performed. These steps are to be regarded as part of the string prescription. They are introduced ad hoc to meet invariance and unitarity requirements. However, in these introductory lectures we give a description only of the integration over geometries (Lecture VII). The GSO projection, and related questions of modular invariance and unitarity are beyond the scope of these
Introductory lectures on conformal field theory and strings
International Nuclear Information System (INIS)
Randjbar-Daemi, S.; Strathdee, J.
1990-01-01
The aim of these lectures is to provide an introduction to a first quantized formulation of string theory. This amounts to developing a consistent set of prescriptions for the perturbative computation of on-shell string amplitudes. The principal tool in this development is 2-dimensional conformal field theory on oriented manifolds of finite genus without boundaries (we treat only closed strings). This class of theory is much simpler than 4-dimensional quantum gravity with which it has many similarities. The geometry is not dynamical in this case, and the matter fields are not sensitive to local features of the geometry but only to global properties which can be characterized by a finite set of parameters (moduli). This can be formulated as field theory on a Riemann surface. We specialize mainly to free field theories for which the quantization problem can be completely solved by elementary means. An introduction to the general case will be given in Lectures II and III where the algebraic approach is discussed. The mathematics of Riemann surfaces is a well developed subject whose formalism is reviewed along with some of the principal theorems in Lecture IV. Physical string states are realized in the Hilbert space of a conformal field theory by the action of so-called ''vertex operators'' on the field theory vacuum state. Correlation functions of these vertex operators serve as ingredients for the computation of string amplitudes. They are to be integrated so as to include the contributions of all conformally inequivalent geometries, and a further manipulation (the GSO projection) is to be performed. These steps are to be regarded as part of the string prescription. The are introduced ad hoc to meet invariance and unitarity requirements. However, in these introductory lectures we give a description only of the integration over geometries (Lecture VII). The GSO projection, and related questions of modular invariance and unitarity are beyond the scope of these lectures
Long, partial-short, and special conformal fields
Energy Technology Data Exchange (ETDEWEB)
Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, Moscow 119991 (Russian Federation)
2016-05-17
In the framework of metric-like approach, totally symmetric arbitrary spin bosonic conformal fields propagating in flat space-time are studied. Depending on the values of conformal dimension, spin, and dimension of space-time, we classify all conformal field as long, partial-short, short, and special conformal fields. An ordinary-derivative (second-derivative) Lagrangian formulation for such conformal fields is obtained. The ordinary-derivative Lagrangian formulation is realized by using double-traceless gauge fields, Stueckelberg fields, and auxiliary fields. Gauge-fixed Lagrangian invariant under global BRST transformations is obtained. The gauge-fixed BRST Lagrangian is used for the computation of partition functions for all conformal fields. Using the result for the partition functions, numbers of propagating D.o.F for the conformal fields are also found.
Remarks on the quantization of conformal fields
International Nuclear Information System (INIS)
Bakas, I.
1988-01-01
The quantization of a general (b,c) system in two dimensions is formulated in terms of an infinite hierarchy of modules for the Virasoro algebra that interpolate between the space of classical conformal fields of weight j and the Dirac sea of semi-infinite forms. This provides a natural framework in which to study the relation between algebraic geometry and representations of the Virasoro algebra with central charge c j = -2(6j 2 -6j+1). The importance of the construction is discussed in the context of string theory. (orig.)
Relating c 0 conformal field theories
International Nuclear Information System (INIS)
Guruswamy, S.; Ludwig, A.W.W.
1998-03-01
A 'canonical mapping' is established between the c = -1 system of bosonic ghosts at the c = 2 complex scalar theory and, a similar mapping between the c = -2 system of fermionic ghosts and the c = 1 Dirac theory. The existence of this mapping is suggested by the identity of the characters of the respective theories. The respective c 0 theories share the same space of states, whereas the spaces of conformal fields are different. Upon this mapping from their c 0) complex scalar and the Dirac theories inherit hidden nonlocal sl(2) symmetries. (author)
Exclusion Statistics in Conformal Field Theory Spectra
International Nuclear Information System (INIS)
Schoutens, K.
1997-01-01
We propose a new method for investigating the exclusion statistics of quasiparticles in conformal field theory (CFT) spectra. The method leads to one-particle distribution functions, which generalize the Fermi-Dirac distribution. For the simplest SU(n) invariant CFTs we find a generalization of Gentile parafermions, and we obtain new distributions for the simplest Z N -invariant CFTs. In special examples, our approach reproduces distributions based on 'fractional exclusion statistics' in the sense of Haldane. We comment on applications to fractional quantum Hall effect edge theories. copyright 1997 The American Physical Society
Bootstrapping conformal field theories with the extremal functional method.
El-Showk, Sheer; Paulos, Miguel F
2013-12-13
The existence of a positive linear functional acting on the space of (differences between) conformal blocks has been shown to rule out regions in the parameter space of conformal field theories (CFTs). We argue that at the boundary of the allowed region the extremal functional contains, in principle, enough information to determine the dimensions and operator product expansion (OPE) coefficients of an infinite number of operators appearing in the correlator under analysis. Based on this idea we develop the extremal functional method (EFM), a numerical procedure for deriving the spectrum and OPE coefficients of CFTs lying on the boundary (of solution space). We test the EFM by using it to rederive the low lying spectrum and OPE coefficients of the two-dimensional Ising model based solely on the dimension of a single scalar quasiprimary--no Virasoro algebra required. Our work serves as a benchmark for applications to more interesting, less known CFTs in the near future.
On the large N limit of conformal field theory
International Nuclear Information System (INIS)
Halpern, M.B.
2003-01-01
Following recent advances in large N matrix mechanics, I discuss here the free (Cuntz) algebraic formulation of the large N limit of two-dimensional conformal field theories of chiral adjoint fermions and bosons. One of the central results is a new affine free algebra which describes a large N limit of su(N) affine Lie algebra. Other results include the associated free-algebraic partition functions and characters, a free-algebraic coset construction, free-algebraic construction of osp(1|2), free-algebraic vertex operator constructions in the large N Bose systems, and a provocative new free-algebraic factorization of the ordinary Koba-Nielsen factor
Heterotic string solutions and coset conformal field theories
Giveon, Amit; Tseytlin, Arkady A
1993-01-01
We discuss solutions of the heterotic string theory which are analogous to bosonic and superstring backgrounds related to coset conformal field theories. A class of exact `left-right symmetric' solutions is obtained by supplementing the metric, antisymmetric tensor and dilaton of the superstring solutions by the gauge field background equal to the generalised Lorentz connection with torsion. As in the superstring case, these backgrounds are $\\a'$-independent, i.e. have a `semiclassical' form. The corresponding heterotic string sigma model is obtained from the combination of the (1,0) supersymmetric gauged WZNW action with the action of internal fermions coupled to the target space gauge field. The pure (1,0) supersymmetric gauged WZNW theory is anomalous and does not describe a consistent heterotic string solution. We also find (to the order $\\alpha'^3$) a two-dimensional perturbative heterotic string solution with the trivial gauge field background. To the leading order in $\\alpha'$ it coincides with the kno...
Schuler, Michael; Whitsitt, Seth; Henry, Louis-Paul; Sachdev, Subir; Läuchli, Andreas M
2016-11-18
The low-energy spectra of many body systems on a torus, of finite size L, are well understood in magnetically ordered and gapped topological phases. However, the spectra at quantum critical points separating such phases are largely unexplored for (2+1)D systems. Using a combination of analytical and numerical techniques, we accurately calculate and analyze the low-energy torus spectrum at an Ising critical point which provides a universal fingerprint of the underlying quantum field theory, with the energy levels given by universal numbers times 1/L. We highlight the implications of a neighboring topological phase on the spectrum by studying the Ising* transition (i.e. the transition between a Z_{2} topological phase and a trivial paramagnet), in the example of the toric code in a longitudinal field, and advocate a phenomenological picture that provides qualitative insight into the operator content of the critical field theory.
Conformal Nets II: Conformal Blocks
Bartels, Arthur; Douglas, Christopher L.; Henriques, André
2017-08-01
Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.
Arbitrary spin conformal fields in (A)dS
International Nuclear Information System (INIS)
Metsaev, R.R.
2014-01-01
Totally symmetric arbitrary spin conformal fields in (A)dS space of even dimension greater than or equal to four are studied. Ordinary-derivative and gauge invariant Lagrangian formulation for such fields is obtained. Gauge symmetries are realized by using auxiliary fields and Stueckelberg fields. We demonstrate that Lagrangian of conformal field is decomposed into a sum of gauge invariant Lagrangians for massless, partial-massless, and massive fields. We obtain a mass spectrum of the partial-massless and massive fields and confirm the conjecture about the mass spectrum made in the earlier literature. In contrast to conformal fields in flat space, the kinetic terms of conformal fields in (A)dS space turn out to be diagonal with respect to fields entering the Lagrangian. Explicit form of conformal transformation which maps conformal field in flat space to conformal field in (A)dS space is obtained. Covariant Lorentz-like and de-Donder like gauge conditions leading to simple gauge-fixed Lagrangian of conformal fields are proposed. Using such gauge-fixed Lagrangian, which is invariant under global BRST transformations, we explain how the partition function of conformal field is obtained in the framework of our approach
Twisted conformal field theories and Morita equivalence
Energy Technology Data Exchange (ETDEWEB)
Marotta, Vincenzo [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' and INFN, Sezione di Napoli, Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy); Naddeo, Adele [CNISM, Unita di Ricerca di Salerno and Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, Via Salvador Allende, 84081 Baronissi (Italy); Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' , Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy)], E-mail: adelenaddeo@yahoo.it
2009-04-01
The Morita equivalence for field theories on noncommutative two-tori is analysed in detail for rational values of the noncommutativity parameter {theta} (in appropriate units): an isomorphism is established between an Abelian noncommutative field theory (NCFT) and a non-Abelian theory of twisted fields on ordinary space. We focus on a particular conformal field theory (CFT), the one obtained by means of the m-reduction procedure [V. Marotta, J. Phys. A 26 (1993) 3481; V. Marotta, Mod. Phys. Lett. A 13 (1998) 853; V. Marotta, Nucl. Phys. B 527 (1998) 717; V. Marotta, A. Sciarrino, Mod. Phys. Lett. A 13 (1998) 2863], and show that it is the Morita equivalent of a NCFT. Finally, the whole m-reduction procedure is shown to be the image in the ordinary space of the Morita duality. An application to the physics of a quantum Hall fluid at Jain fillings {nu}=m/(2pm+1) is explicitly discussed in order to further elucidate such a correspondence and to clarify its role in the physics of strongly correlated systems. A new picture emerges, which is very different from the existing relationships between noncommutativity and many body systems [A.P. Polychronakos, arXiv: 0706.1095].
Nonunitary Lagrangians and Unitary Non-Lagrangian Conformal Field Theories
Buican, Matthew; Laczko, Zoltan
2018-02-01
In various dimensions, we can sometimes compute observables of interacting conformal field theories (CFTs) that are connected to free theories via the renormalization group (RG) flow by computing protected quantities in the free theories. On the other hand, in two dimensions, it is often possible to algebraically construct observables of interacting CFTs using free fields without the need to explicitly construct an underlying RG flow. In this Letter, we begin to extend this idea to higher dimensions by showing that one can compute certain observables of an infinite set of unitary strongly interacting four-dimensional N =2 superconformal field theories (SCFTs) by performing simple calculations involving sets of nonunitary free four-dimensional hypermultiplets. These free fields are distant cousins of the Majorana fermion underlying the two-dimensional Ising model and are not obviously connected to our interacting theories via an RG flow. Rather surprisingly, this construction gives us Lagrangians for particular observables in certain subsectors of many "non-Lagrangian" SCFTs by sacrificing unitarity while preserving the full N =2 superconformal algebra. As a by-product, we find relations between characters in unitary and nonunitary affine Kac-Moody algebras. We conclude by commenting on possible generalizations of our construction.
Nonunitary Lagrangians and Unitary Non-Lagrangian Conformal Field Theories.
Buican, Matthew; Laczko, Zoltan
2018-02-23
In various dimensions, we can sometimes compute observables of interacting conformal field theories (CFTs) that are connected to free theories via the renormalization group (RG) flow by computing protected quantities in the free theories. On the other hand, in two dimensions, it is often possible to algebraically construct observables of interacting CFTs using free fields without the need to explicitly construct an underlying RG flow. In this Letter, we begin to extend this idea to higher dimensions by showing that one can compute certain observables of an infinite set of unitary strongly interacting four-dimensional N=2 superconformal field theories (SCFTs) by performing simple calculations involving sets of nonunitary free four-dimensional hypermultiplets. These free fields are distant cousins of the Majorana fermion underlying the two-dimensional Ising model and are not obviously connected to our interacting theories via an RG flow. Rather surprisingly, this construction gives us Lagrangians for particular observables in certain subsectors of many "non-Lagrangian" SCFTs by sacrificing unitarity while preserving the full N=2 superconformal algebra. As a by-product, we find relations between characters in unitary and nonunitary affine Kac-Moody algebras. We conclude by commenting on possible generalizations of our construction.
Takiff superalgebras and conformal field theory
International Nuclear Information System (INIS)
Babichenko, Andrei; Ridout, David
2013-01-01
A class of non-semisimple extensions of Lie superalgebras is studied. They are obtained by adjoining to the superalgebra its adjoint representation as an Abelian ideal. When the superalgebra is of affine Kac–Moody type, a generalization of Sugawara’s construction is shown to give rise to a copy of the Virasoro algebra and so, presumably, to a conformal field theory. Evidence for this is detailed for the extension of the affinization of the superalgebra gl( 1|1): its highest weight irreducible modules are classified using spectral flow, the irreducible supercharacters are computed and a continuum version of the Verlinde formula is verified to give non-negative integer structure coefficients. Interpreting these coefficients as those of the Grothendieck ring of fusion, partial results on the true fusion ring and its indecomposable structures are deduced. (paper)
Particle versus field structure in conformal quantum field theories
International Nuclear Information System (INIS)
Schroer, Bert
2000-06-01
I show that a particle structure in conformal field theory is incompatible with interactions. As a substitute one has particle-like excitations whose interpolating fields have in addition to their canonical dimension an anomalous contribution. The spectra of anomalous dimension is given in terms of the Lorentz invariant quadratic invariant (compact mass operator) of a conformal generator R μ with pure discrete spectrum. The perturbative reading of R o as a Hamiltonian in its own right, associated with an action in a functional integral setting naturally leads to the Ad S formulation. The formal service role of Ad S in order to access C QFT by a standard perturbative formalism (without being forced to understand first massive theories and then taking their scale-invariant limit) vastly increases the realm of conventionally accessible 4-dim. C QFT beyond those for which one had to use Lagrangians with supersymmetry in order to have a vanishing Beta-function. (author)
International Nuclear Information System (INIS)
Fredenhagen, K.; Joerss, M.
1994-10-01
Starting from a chiral conformal Haag-Kastler net on 2 dimensional Minkowski space we construct associated pointlike localized fields. This amounts to a proof of the existence of operator product expansions. We derive the result in two ways. One is based on the geometrical identification of the modular structure, the other depends on a ''conformal cluster theorem'' of the conformal two-point-functions in algebraic quantum field theory. The existence of the fields then implies important structural properties of the theory, as PCT-invariance, the Bisognano-Wichmann identification of modular operators, Haag duality and additivity. (orig.)
Boundary states in c=-2 logarithmic conformal field theory
International Nuclear Information System (INIS)
Bredthauer, Andreas; Flohr, Michael
2002-01-01
Starting from first principles, a constructive method is presented to obtain boundary states in conformal field theory. It is demonstrated that this method is well suited to compute the boundary states of logarithmic conformal field theories. By studying the logarithmic conformal field theory with central charge c=-2 in detail, we show that our method leads to consistent results. In particular, it allows to define boundary states corresponding to both, indecomposable representations as well as their irreducible subrepresentations
Lattice models and conformal field theories
International Nuclear Information System (INIS)
Saleur, H.
1988-01-01
Theoretical studies concerning the connection between critical physical systems and the conformal theories are reviewed. The conformal theory associated to a critical (integrable) lattice model is derived. The obtention of the central charge, critical exponents and torus partition function, using renormalization group arguments, is shown. The quantum group structure, in the integrable lattice models, and the theory of Visaro algebra representations are discussed. The relations between off-critical integrable models and conformal theories, in finite geometries, are studied
Conformal Vector Fields on Doubly Warped Product Manifolds and Applications
Directory of Open Access Journals (Sweden)
H. K. El-Sayied
2016-01-01
Full Text Available This article aimed to study and explore conformal vector fields on doubly warped product manifolds as well as on doubly warped spacetime. Then we derive sufficient conditions for matter and Ricci collineations on doubly warped product manifolds. A special attention is paid to concurrent vector fields. Finally, Ricci solitons on doubly warped product spacetime admitting conformal vector fields are considered.
C-metric solution for conformal gravity with a conformally coupled scalar field
Energy Technology Data Exchange (ETDEWEB)
Meng, Kun, E-mail: mengkun@tjpu.edu.cn [School of Science, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, Liu, E-mail: lzhao@nankai.edu.cn [School of Physics, Nankai University, Tianjin 300071 (China)
2017-02-15
The C-metric solution of conformal gravity with a conformally coupled scalar field is presented. The solution belongs to the class of Petrov type D spacetimes and is conformal to the standard AdS C-metric appeared in vacuum Einstein gravity. For all parameter ranges, we identify some of the physically interesting static regions and the corresponding coordinate ranges. The solution may contain a black hole event horizon, an acceleration horizon, either of which may be cut by the conformal infinity or be hidden behind the conformal infinity. Since the model is conformally invariant, we also discussed the possible effects of the conformal gauge choices on the structure of the spacetime.
Dimensional analysis in field theory
International Nuclear Information System (INIS)
Stevenson, P.M.
1981-01-01
Dimensional Transmutation (the breakdown of scale invariance in field theories) is reconciled with the commonsense notions of Dimensional Analysis. This makes possible a discussion of the meaning of the Renormalisation Group equations, completely divorced from the technicalities of renormalisation. As illustrations, I describe some very farmiliar QCD results in these terms
Note on Weyl versus conformal invariance in field theory
Energy Technology Data Exchange (ETDEWEB)
Wu, Feng [Nanchang University, Department of Physics, Nanchang (China)
2017-12-15
It was argued recently that conformal invariance in flat spacetime implies Weyl invariance in a general curved background for unitary theories and possible anomalies in the Weyl variation of scalar operators are identified. We argue that generically unitarity alone is not sufficient for a conformal field theory to be Weyl invariant. Furthermore, we show explicitly that when a unitary conformal field theory couples to gravity in a Weyl-invariant way, each primary scalar operator that is either relevant or marginal in the unitary conformal field theory corresponds to a Weyl-covariant operator in the curved background. (orig.)
Very special conformal field theories and their holographic duals
Nakayama, Yu
2018-03-01
Cohen and Glashow introduced the notion of very special relativity as viable space-time symmetry of elementary particle physics. As a natural generalization of their idea, we study the subgroup of the conformal group, dubbed very special conformal symmetry, which is an extension of the very special relativity. We classify all of them and construct field theory examples as well as holographic realization of the very special conformal field theories.
Method of solving conformal models in D-dimensional space I
International Nuclear Information System (INIS)
Fradkin, E.S.; Palchik, M.Y.
1996-01-01
We study the Hilbert space of conformal field theory in D-dimensional space. The latter is shown to have model-independent structure. The states of matter fields and gauge fields form orthogonal subspaces. The dynamical principle fixing the choice of model may be formulated either in each of these subspaces or in their direct sum. In the latter case, gauge interactions are necessarily present in the model. We formulate the conditions specifying the class of models where gauge interactions are being neglected. The anomalous Ward identities are derived. Different values of anomalous parameters (D-dimensional analogs of a central charge, including operator ones) correspond to different models. The structure of these models is analogous to that of 2-dimensional conformal theories. Each model is specified by D-dimensional analog of null vector. The exact solutions of the simplest models of this type are examined. It is shown that these models are equivalent to Lagrangian models of scalar fields with a triple interaction. The values of dimensions of such fields are calculated, and the closed sets of differential equations for higher Green functions are derived. Copyright copyright 1996 Academic Press, Inc
Boundary conformal field theory and the worldsheet approach to D-branes
Recknagel, Andreas
2013-01-01
Boundary conformal field theory is concerned with a class of two-dimensional quantum field theories which display a rich mathematical structure and have many applications ranging from string theory to condensed matter physics. In particular, the framework allows discussion of strings and branes directly at the quantum level. Written by internationally renowned experts, this comprehensive introduction to boundary conformal field theory reaches from theoretical foundations to recent developments, with an emphasis on the algebraic treatment of string backgrounds. Topics covered include basic concepts in conformal field theory with and without boundaries, the mathematical description of strings and D-branes, and the geometry of strongly curved spacetime. The book offers insights into string geometry that go beyond classical notions. Describing the theory from basic concepts, and providing numerous worked examples from conformal field theory and string theory, this reference is of interest to graduate students and...
Three dimensional field computation
International Nuclear Information System (INIS)
Trowbridge, C.W.
1981-06-01
Recent research work carried out at Rutherford and Appleton Laboratories into the Computation of Electromagnetic Fields is summarised. The topics covered include algorithms for integral and differential methods for the solution of 3D magnetostatic fields, comparison of results with experiment and an investigation into the strengths and weaknesses of both methods for an analytic problem. The paper concludes with a brief summary of the work in progress on the solution of 3D eddy currents using differential finite elements. (author)
Conformal field theory, triality and the Monster group
International Nuclear Information System (INIS)
Dolan, L.; Goddard, P.; Montague, P.
1990-01-01
From an even self-dual N-dimensional lattice, Λ, it is always possible to construct two (chiral) conformal field theories, an untwisted theory H (Λ), and a Z 2 -twisted theory H (Λ), constructed using the reflection twist. (N must be a multiple of 8 and the theories are modular invariant if it is a multiple of 24.) Similarly, from a doubly-even self-dual binary code C, it is possible to construct two even self-dual lattices, an untwisted one Λ C and a twisted one anti Λ C . It is shown that H(Λ C ) always has a triality structure, and that this triality induces first an isomorphism H(anti Λ C )≅H(Λ C ) and, through this, a triality of H(anti Λ C ). In the case where C is the Golay code, anti Λ C is the Leech lattice and the induced triality is the extra symmetry necessary to generate the Monster group from (an extension of) Conway's group. Thus it is demonstrated that triality is a generic symmetry. The induced isomorphism accounts for all 9 of the coincidences between the 48 conformal field theories H(Λ) and H(Λ) with N=24. (orig.)
Stochastic Loewner evolution as an approach to conformal field theory
International Nuclear Information System (INIS)
Mueller-Lohmann, Annekathrin
2008-01-01
The main focus on this work lies on the relationship between two-dimensional boundary Conformal Field Theories (BCFTs) and SCHRAMM-LOEWNER Evolutions (SLEs) as motivated by their connection to the scaling limit of Statistical Physics models at criticality. The BCFT approach used for the past 25 years is based on the algebraic formulation of local objects such as fields and their correlations in these models. Introduced in 1999, SLE describes the physical properties from a probabilistic point of view, studying measures on growing curves, i.e. global objects such as cluster interfaces. After a short motivation of the topic, followed by a more detailed introduction to two-dimensional boundary Conformal Field Theory and SCHRAMM-LOEWNER Evolution, we present the results of our original work. We extend the method of obtaining SLE variants for a change of measure of the single SLE to derive the most general BCFT model that can be related to SLE. Moreover, we interpret the change of the measure in the context of physics and Probability Theory. In addition, we discuss the meaning of bulk fields in BCFT as bulk force-points for the SLE variant SLE (κ, vector ρ). Furthermore, we investigate the short-distance expansion of the boundary condition changing fields, creating cluster interfaces that can be described by SLE, with other boundary or bulk fields. Thereby we derive new SLE martingales related to the existence of boundary fields with vanishing descendant on level three. We motivate that the short-distance scaling law of these martingales as adjustment of the measure can be interpreted as the SLE probability of curves coming close to the location of the second field. Finally, we extend the algebraic κ-relation for the allowed variances in multiple SLE, arising due to the commutation requirement of the infinitesimal growth operators, to the joint growth of two SLE traces. The analysis straightforwardly suggests the form of the infinitesimal LOEWNER mapping of joint
Introduction to conformal field theory. With applications to string theory
International Nuclear Information System (INIS)
Blumenhagen, Ralph; Plauschinn, Erik
2009-01-01
Based on class-tested notes, this text offers an introduction to Conformal Field Theory with a special emphasis on computational techniques of relevance for String Theory. It introduces Conformal Field Theory at a basic level, Kac-Moody algebras, one-loop partition functions, Superconformal Field Theories, Gepner Models and Boundary Conformal Field Theory. Eventually, the concept of orientifold constructions is explained in detail for the example of the bosonic string. In providing many detailed CFT calculations, this book is ideal for students and scientists intending to become acquainted with CFT techniques relevant for string theory but also for students and non-specialists from related fields. (orig.)
Conformal field theories, representations and lattice constructions
International Nuclear Information System (INIS)
Dolan, L.; Montague, P.
1996-01-01
An account is given of the structure and representations of chiral bosonic meromorphic conformal field theories (CFT's), and, in particular, the conditions under which such a CFT may be extended by a representation to form a new theory. This general approach is illustrated by considering the untwisted and Z 2 -twisted theories, H(Λ) and H(Λ) respectively, which may be constructed from a suitable even Euclidean lattice Λ. Similarly, one may construct lattices Λ C and Lambda C by analogous constructions from a doubly-even binary code C. In the case when C is self-dual, the corresponding lattices are also. Similarly, H(Λ) and H(Λ) are self-dual if and only if Λ is. We show that H(Λ C ) has a natural triality structure, which induces an isomorphism H(Λ C )≡H(Λ C ) and also a triality structure on H(Λ C ). For C the Golay code, Λ C is the Leech lattice, and the triality on H(Λ C ) is the symmetry which extends the natural action of (an extension of) Conway's group on this theory to the Monster, so setting triality and Frenkel, Lepowsky and Meurman's construction of the natural Monster module in a more general context. The results also serve to shed some light on the classification of self-dual CFT's. We find that of the 48 theories H(Λ) and H(Λ) with central charge 24 that there are 39 distinct ones, and further that all 9 coincidences are accounted for by the isomorphism detailed above, induced by the existence of a doubly-even self-dual binary code. (orig.). With 8 figs., 2 tabs
Modular constraints on conformal field theories with currents
Bae, Jin-Beom; Lee, Sungjay; Song, Jaewon
2017-12-01
We study constraints coming from the modular invariance of the partition function of two-dimensional conformal field theories. We constrain the spectrum of CFTs in the presence of holomorphic and anti-holomorphic currents using the semi-definite programming. In particular, we find the bounds on the twist gap for the non-current primaries depend dramatically on the presence of holomorphic currents, showing numerous kinks and peaks. Various rational CFTs are realized at the numerical boundary of the twist gap, saturating the upper limits on the degeneracies. Such theories include Wess-Zumino-Witten models for the Deligne's exceptional series, the Monster CFT and the Baby Monster CFT. We also study modular constraints imposed by W -algebras of various type and observe that the bounds on the gap depend on the choice of W -algebra in the small central charge region.
Genus two partition functions of extremal conformal field theories
International Nuclear Information System (INIS)
Gaiotto, Davide; Yin Xi
2007-01-01
Recently Witten conjectured the existence of a family of 'extremal' conformal field theories (ECFTs) of central charge c = 24k, which are supposed to be dual to three-dimensional pure quantum gravity in AdS 3 . Assuming their existence, we determine explicitly the genus two partition functions of k = 2 and k = 3 ECFTs, using modular invariance and the behavior of the partition function in degenerating limits of the Riemann surface. The result passes highly nontrivial tests and in particular provides a piece of evidence for the existence of the k = 3 ECFT. We also argue that the genus two partition function of ECFTs with k ≤ 10 are uniquely fixed (if they exist)
Mixed global anomalies and boundary conformal field theories
Numasawa, Tokiro; Yamaguchi, Satoshi
2017-01-01
We consider the relation of mixed global gauge gravitational anomalies and boundary conformal field theory in WZW models for simple Lie groups. The discrete symmetries of consideration are the centers of the simple Lie groups. These mixed anomalies prevent to gauge them i.e, take the orbifold by the center. The absence of anomalies impose conditions on the levels of WZW models. Next, we study the conformal boundary conditions for the original theories. We consider the existence of a conformal...
Flat connection, conformal field theory and quantum group
International Nuclear Information System (INIS)
Kato, Mitsuhiro.
1989-07-01
General framework of linear first order differential equation for four-point conformal block is studied by using flat connection. Integrability and SL 2 invariance restrict possible form of flat connection. Under a special ansatz classical Yang-Baxter equation appears as an integrability condition and the WZW model turns to be unique conformal field theory in that case. Monodromy property of conformal block can be easily determined by the flat connection. 11 refs
Stimato, Gerardina; Ippolito, Edy; Silipigni, Sonia; Venanzio, Cristina Di; Gaudino, Diego; Fiore, Michele; Trodella, Lucio; D'Angelillo, Rolando Maria; Ramella, Sara
2016-01-01
Objective: To develop an alternative three-dimensional treatment plan with standardized fields class solution for whole-breast radiotherapy in patients with large/pendulous breast and/or high body mass index (BMI). Methods: Two treatment plans [tangential fields and standardized five-fields technique (S5F)] for a total dose of 50 Gy/25 fractions were generated for patients with large breasts [planning target volume (PTV) >1000 cm3 and/or BMI >25 kg m−2], supine positioned. S5F plans consist of two wedged tangential beams, anteroposterior: 20° for the right breast and 340° for the left breast, and posteroanterior: 181° for the right breast and 179° for the left breast. A field in field in medial–lateral beam and additional fields were added to reduce hot spot areas and extra–target-tissue irradiation and to improve dose distribution. The percentage of PTV receiving 95% of the prescribed dose (PTV V95%), percentage of PTV receiving 105% of the prescribed dose (PTV V105%), maximal dose to PTV (PTV Dmax), homogeneity index (HI) and conformity index were recorded. V10%, V20%, V105% and V107% of a “proper” normal tissue structure (body-PTV healthy tissue) were recorded. Statistical analyses were performed using SYSTAT v.12.0 (SPSS, Chicago, IL). Results: In 38 patients included, S5F improved HI (8.4 vs 10.1; p ≤ 0.001) and significantly reduced PTV Dmax and PTV V105%. The extra–target-tissue irradiation was significantly reduced using S5F for V105% (cm3) and V107% (cm3) with a very high difference in tissue irradiation (46.6 vs 3.0 cm3, p ≤ 0.001 for V105% and 12.2 vs 0.0 cm3, p ≤ 0.001 for V107% for tangential field and S5F plans, respectively). Only a slight increase in low-dose extra–target-tissue irradiation (V10%) was observed (2.2719 vs 1.8261 cm3, p = 0.002). Conclusion: The S5F technique in patients with large breast or high BMI increases HI and decreases hot spots in extra-target-tissues and can therefore be
Black Hole Monodromy and Conformal Field Theory
Castro, A.; Lapan, J.M.; Maloney, A.; Rodriguez, M.J.
2013-01-01
The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a nonextremal black hole, and it explains why features of the inner event
Dimension shifting operators and null states in 2D conformally invariant field theories
International Nuclear Information System (INIS)
Gervais, J.L.
1986-01-01
We discuss the existence and properties of differential operators which transform covariant operators into covariant operators of different weights in two-dimensional conformally invariant field theories. We relate them to null states and the vanishing of the Kac determinant in representations of the conformal algebra, and to the existence of differential equations for Green functions of covariant operators. In this framework, we rederive the essential features of our earlier work on dual models with shifted intercept, which in euclidean space-time gives explicit solutions of the conformal bootstrap equations where all operators are marginal. (orig.)
Markov traces and II1 factors in conformal field theory
International Nuclear Information System (INIS)
Boer, J. de; Goeree, J.
1991-01-01
Using the duality equations of Moore and Seiberg we define for every primary field in a Rational Conformal Field Theory a proper Markov trace and hence a knot invariant. Next we define two nested algebras and show, using results of Ocneanu, how the position of the smaller algebra in the larger one reproduces part of the duality data. A new method for constructing Rational Conformal Field Theories is proposed. (orig.)
International Nuclear Information System (INIS)
Luescher, M.
1975-11-01
Let phi 1 (x) and phi 2 (y) be two local fields in a conformal quantum field theory (CQFT) in two-dimensional spacetime. It is then shown that the vector-valued distribution phi 1 (x) phi 2 (y) /0 > is a boundary value of a vector-valued holomorphic function which is defined on a large conformally invariant domain. By group theoretical arguments alone it is proved that phi 1 (x) phi 2 (y) /0 > can be expanded into conformal partial waves. These have all the properties of a global version of Wilson's operator product expansions when applied to the vacuum state /0 >. Finally, the corresponding calculations are carried out more explicitly in the Thirring model. Here, a complete set of local conformally covariant fields is found, which is closed under vacuum expansion of any two of its elements (a vacuum expansion is an operator product expansion applied to the vacuum). (orig.) [de
Conformal field theory on surfaces with boundaries and nondiagonal modular invariants
International Nuclear Information System (INIS)
Bern, Z.; Dunbar, D.C.
1990-01-01
This paper shows that the operator content of a conformal field theory defined on surfaces with boundaries and crosscaps is more restricted when the periodic sector is described by nondiagonal modular invariants than in the case of diagonal modular invariants. By tensoring, the restrictions can be alleviated, leading to a rich structure. Such constrictions are useful, for example, in lower- dimensional open superstring models
Warped conformal field theory as lower spin gravity
Hofman, Diego M.; Rollier, Blaise
2015-08-01
Two dimensional Warped Conformal Field Theories (WCFTs) may represent the simplest examples of field theories without Lorentz invariance that can be described holographically. As such they constitute a natural window into holography in non-AdS space-times, including the near horizon geometry of generic extremal black holes. It is shown in this paper that WCFTs posses a type of boost symmetry. Using this insight, we discuss how to couple these theories to background geometry. This geometry is not Riemannian. We call it Warped Geometry and it turns out to be a variant of a Newton-Cartan structure with additional scaling symmetries. With this formalism the equivalent of Weyl invariance in these theories is presented and we write two explicit examples of WCFTs. These are free fermionic theories. Lastly we present a systematic description of the holographic duals of WCFTs. It is argued that the minimal setup is not Einstein gravity but an SL (2, R) × U (1) Chern-Simons Theory, which we call Lower Spin Gravity. This point of view makes manifest the definition of boundary for these non-AdS geometries. This case represents the first step towards understanding a fully invariant formalism for WN field theories and their holographic duals.
Warped conformal field theory as lower spin gravity
Directory of Open Access Journals (Sweden)
Diego M. Hofman
2015-08-01
Full Text Available Two dimensional Warped Conformal Field Theories (WCFTs may represent the simplest examples of field theories without Lorentz invariance that can be described holographically. As such they constitute a natural window into holography in non-AdS space–times, including the near horizon geometry of generic extremal black holes. It is shown in this paper that WCFTs posses a type of boost symmetry. Using this insight, we discuss how to couple these theories to background geometry. This geometry is not Riemannian. We call it Warped Geometry and it turns out to be a variant of a Newton–Cartan structure with additional scaling symmetries. With this formalism the equivalent of Weyl invariance in these theories is presented and we write two explicit examples of WCFTs. These are free fermionic theories. Lastly we present a systematic description of the holographic duals of WCFTs. It is argued that the minimal setup is not Einstein gravity but an SL(2,R×U(1 Chern–Simons Theory, which we call Lower Spin Gravity. This point of view makes manifest the definition of boundary for these non-AdS geometries. This case represents the first step towards understanding a fully invariant formalism for WN field theories and their holographic duals.
International Nuclear Information System (INIS)
Zamolodchikov, A.B.
1987-01-01
A multipoint conformal block of Ramond states of the two-dimensional free scalar field is calculated. This function is related to the free energy of the scalar field on the hyperelliptic Riemann surface under a particular choice of boundary conditions. Being compactified on the circle this field leads to the crossing symmetric correlation functions with a discrete spectrum of scale dimensions. These functions are supposed to describe multipoint spin correlations of the critical Ashkin-Teller model. (orig.)
Dipole-magnet field models based on a conformal map
Directory of Open Access Journals (Sweden)
P. L. Walstrom
2012-10-01
Full Text Available In general, generation of charged-particle transfer maps for conventional iron-pole-piece dipole magnets to third and higher order requires a model for the midplane field profile and its transverse derivatives (soft-edge model to high order and numerical integration of map coefficients. An exact treatment of the problem for a particular magnet requires use of measured magnetic data. However, in initial design of beam transport systems, users of charged-particle optics codes generally rely on magnet models built into the codes. Indeed, if maps to third order are adequate for the problem, an approximate analytic field model together with numerical map coefficient integration can capture the important features of the transfer map. The model described in this paper is based on the fact that, except at very large distances from the magnet, the magnetic field for parallel pole-face magnets with constant pole gap height and wide pole faces is basically two dimensional (2D. The field for all space outside of the pole pieces is given by a single (complex analytic expression and includes a parameter that controls the rate of falloff of the fringe field. Since the field function is analytic in the complex plane outside of the pole pieces, it satisfies two basic requirements of a field model for higher-order map codes: it is infinitely differentiable at the midplane and also a solution of the Laplace equation. It is apparently the only simple model available that combines an exponential approach to the central field with an inverse cubic falloff of field at large distances from the magnet in a single expression. The model is not intended for detailed fitting of magnetic field data, but for use in numerical map-generating codes for studying the effect of extended fringe fields on higher-order transfer maps. It is based on conformally mapping the area between the pole pieces to the upper half plane, and placing current filaments on the pole faces. An
Three level constraints on conformal field theories and string models
International Nuclear Information System (INIS)
Lewellen, D.C.
1989-05-01
Simple tree level constraints for conformal field theories which follow from the requirement of crossing symmetry of four-point amplitudes are presented, and their utility for probing general properties of string models is briefly illustrated and discussed. 9 refs
Notes on the Verlinde formula in nonrational conformal field theories
International Nuclear Information System (INIS)
Jego, Charles; Troost, Jan
2006-01-01
We review and extend evidence for the validity of a generalized Verlinde formula, in particular, nonrational conformal field theories. We identify a subset of representations of the chiral algebra in nonrational conformal field theories that give rise to an analogue of the relation between modular S-matrices and fusion coefficients in rational conformal field theories. To that end we review and extend the Cardy-type brane calculations in bosonic and supersymmetric Liouville theory (and its duals) as well as in H 3 + . We analyze the three-point functions of Liouville theory and of H 3 + in detail to directly identify the fusion coefficients from the operator product expansion. Moreover, we check the validity of a proposed generic formula for localized brane one-point functions in nonrational conformal field theories
Conformal field theory and its application to strings
International Nuclear Information System (INIS)
Verlinde, E.P.
1988-01-01
Conformal field theories on Riemann surfaces are considered and the result is applied to study the loop amplitudes for bosonic strings. It is shown that there is a close resemblance between the loop amplitudes for φ 3 -theory and the expressions for string multi-loop amplitudes. The similarity between φ 3 -amplitudes in curved backgrounds and the analytic structure of string amplitudes in backgrounds described by conformal field theories is also pointed out. 60 refs.; 5 figs.; 200 schemes
Mourits, Daphne L; Remmers, Jelmer S; Tan, Stevie H; Moll, Annette C; Hartong, Dyonne T
2018-04-03
To introduce a novel technique to design individually customized conformers for postenucleation sockets with dermis fat implants. We use a 3-dimensional scan of the frontal face/orbit and eyelid contour to design an individualized conformer. This polymethylmetacrylate printed conformer is adapted to patients' socket, palpebral fissures, horizontal eyelid aperture, curvature of the eyelids, and mean diameter of patients' contralateral eye. Sutures through holes in the inferior part of the conformer and in the extension can be placed to fixate the conformer and anchor fornix deepening sutures. A correct fitting conformer can be printed and attached to the socket and eyelids. The shape of this conformer can be used subsequently postsurgically to design the ocular prosthesis. Presurgical planning is important to anticipate for a functional socket to adequately fit an artificial eye. The presented technique using 3-dimensional imaging, designing, and printing promises to prevent conformer extrusion and forniceal shortening.
Einstein gravity 3-point functions from conformal field theory
Afkhami-Jeddi, Nima; Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein
2017-12-01
We study stress tensor correlation functions in four-dimensional conformal field theories with large N and a sparse spectrum. Theories in this class are expected to have local holographic duals, so effective field theory in anti-de Sitter suggests that the stress tensor sector should exhibit universal, gravity-like behavior. At the linearized level, the hallmark of locality in the emergent geometry is that stress tensor three-point functions 〈 T T T 〉, normally specified by three constants, should approach a universal structure controlled by a single parameter as the gap to higher spin operators is increased. We demonstrate this phenomenon by a direct CFT calculation. Stress tensor exchange, by itself, violates causality and unitarity unless the three-point functions are carefully tuned, and the unique consistent choice exactly matches the prediction of Einstein gravity. Under some assumptions about the other potential contributions, we conclude that this structure is universal, and in particular, that the anomaly coefficients satisfy a ≈ c as conjectured by Camanho et al. The argument is based on causality of a four-point function, with kinematics designed to probe bulk locality, and invokes the chaos bound of Maldacena, Shenker, and Stanford.
Universality of sparse d>2 conformal field theory at large N
Energy Technology Data Exchange (ETDEWEB)
Belin, Alexandre; Boer, Jan de; Kruthoff, Jorrit [Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics,University of Amsterdam, Science Park 904, Amsterdam, 1098 XH The (Netherlands); Michel, Ben; Shaghoulian, Edgar; Shyani, Milind [Department of Physics, University of California,Santa Barbara, CA, 93106 (United States)
2017-03-13
We derive necessary and sufficient conditions for large N conformal field theories to have a universal free energy and an extended range of validity of the higher-dimensional Cardy formula. These constraints are much tighter than in two dimensions and must be satisfied by any conformal field theory dual to Einstein gravity. We construct and analyze symmetric product orbifold theories on T{sup d} and show that they only realize the necessary phase structure and extended range of validity if the seed theory is assumed to have a universal vacuum energy.
Massless fields in curved space-time: The conformal formalism
International Nuclear Information System (INIS)
Castagnino, M.A.; Sztrajman, J.B.
1986-01-01
A conformally invariant theory for massless quantum fields in curved space-time is formulated. We analyze the cases of spin-0, - 1/2 , and -1. The theory is developed in the important case of an ''expanding universe,'' generalizing the particle model of ''conformal transplantation'' known for spin-0 to spins- 1/2 and -1. For the spin-1 case two methods introducing new conformally invariant gauge conditions are stated, and a problem of inconsistency that was stated for spin-1 is overcome
Irreversibility and higher-spin conformal field theory
Anselmi, Damiano
2000-08-01
I discuss the properties of the central charges c and a for higher-derivative and higher-spin theories (spin 2 included). Ordinary gravity does not admit a straightforward identification of c and a in the trace anomaly, because it is not conformal. On the other hand, higher-derivative theories can be conformal, but have negative c and a. A third possibility is to consider higher-spin conformal field theories. They are not unitary, but have a variety of interesting properties. Bosonic conformal tensors have a positive-definite action, equal to the square of a field strength, and a higher-derivative gauge invariance. There exists a conserved spin-2 current (not the canonical stress tensor) defining positive central charges c and a. I calculate the values of c and a and study the operator-product structure. Higher-spin conformal spinors have no gauge invariance, admit a standard definition of c and a and can be coupled to Abelian and non-Abelian gauge fields in a renormalizable way. At the quantum level, they contribute to the one-loop beta function with the same sign as ordinary matter, admit a conformal window and non-trivial interacting fixed points. There are composite operators of high spin and low dimension, which violate the Ferrara-Gatto-Grillo theorem. Finally, other theories, such as conformal antisymmetric tensors, exhibit more severe internal problems. This research is motivated by the idea that fundamental quantum field theories should be renormalization-group (RG) interpolations between ultraviolet and infrared conformal fixed points, and quantum irreversibility should be a general principle of nature.
Electromagnetic field and the theory of conformal and biholomorphic invariants
International Nuclear Information System (INIS)
Lawrynowicz, J.
1976-01-01
This paper contains sections on: 1. Conformal invariance and variational principles in electrodynamics. 2. The principles of Dirichlet and Thomson as a physical motivation for the methods of conformal capacities and extremal lengths. 3. Extension to pseudoriemannian manifolds. 4. Extension to hermitian manifolds. 5. An extension of Schwarz's lemma for hermitian manifolds and its physical significance. 6. Variation of ''complex'' capacities within the admissible class of plurisubharmonic functions. The author concentrates on motivations and interpretations connected with the electromagnetic field. (author)
International Nuclear Information System (INIS)
Fradkin, E.S.; Palchik, M.Ya.
1996-02-01
We study a family of exactly solvable models of conformally-invariant quantum field theory in D-dimensional space. We demonstrate the existence of D-dimensional analogs of primary and secondary fields. Under the action of energy-momentum tensor and conserved currents, the primary fields creates an infinite set of (tensor) secondary fields of different generations. The commutators of secondary fields with zero components of current and energy-momentum tensor include anomalous operator terms. We show that the Hilbert space of conformal theory has a special sector which structure is solely defined by the Ward identities independently on the choice of dynamical model. The states of this sector are constructed from secondary fields. Definite self-consistent conditions on the states of the latter sector fix the choice of the field model uniquely. In particular, Lagrangian models do belong to this class of models. The above self-consistent conditions are formulated as follows. Special superpositions Q s , s = 1,2,... of secondary fields are constructed. Each superposition is determined by the requirement that the form of its commutators with energy-momentum tensor and current (i.e. transformation properties) should be identical to that of a primary field. Each equation Q s (x) = 0 is consistent, and defines an exactly solvable model for D ≥ 3. The structure of these models are analogous to that of well-known two dimensional conformal models. The states Q s (x) modul 0> are analogous to the null-vectors of two dimensional theory. In each of these models one can obtain a closed set of differential equations for all the higher Green functions, as well as algebraic equations relating the scale dimension of fundamental field to the D-dimensional analog of a central charge. As an example, we present a detailed discussion of a pair of exactly solvable models in even-dimensional space D ≥ 4. (author). 28 refs
Noncommutative Geometry in M-Theory and Conformal Field Theory
Energy Technology Data Exchange (ETDEWEB)
Morariu, Bogdan [Univ. of California, Berkeley, CA (United States)
1999-05-01
In the first part of the thesis I will investigate in the Matrix theory framework, the subgroup of dualities of the Discrete Light Cone Quantization of M-theory compactified on tori, which corresponds to T-duality in the auxiliary Type II string theory. After a review of matrix theory compactification leading to noncommutative supersymmetric Yang-Mills gauge theory, I will present solutions for the fundamental and adjoint sections on a two-dimensional twisted quantum torus and generalize to three-dimensional twisted quantum tori. After showing how M-theory T-duality is realized in supersymmetric Yang-Mills gauge theories on dual noncommutative tori I will relate this to the mathematical concept of Morita equivalence of C*-algebras. As a further generalization, I consider arbitrary Ramond-Ramond backgrounds. I will also discuss the spectrum of the toroidally compactified Matrix theory corresponding to quantized electric fluxes on two and three tori. In the second part of the thesis I will present an application to conformal field theory involving quantum groups, another important example of a noncommutative space. First, I will give an introduction to Poisson-Lie groups and arrive at quantum groups using the Feynman path integral. I will quantize the symplectic leaves of the Poisson-Lie group SU(2)*. In this way we obtain the unitary representations of U_{q}(SU(2)). I discuss the X-structure of SU(2)* and give a detailed description of its leaves using various parametrizations. Then, I will introduce a new reality structure on the Heisenberg double of Fun_{q} (SL(N,C)) for q phase, which can be interpreted as the quantum phase space of a particle on the q-deformed mass-hyperboloid. I also present evidence that the above real form describes zero modes of certain non-compact WZNW-models.
Noncommutative Geometry in M-Theory and Conformal Field Theory
International Nuclear Information System (INIS)
Morariu, Bogdan
1999-01-01
In the first part of the thesis I will investigate in the Matrix theory framework, the subgroup of dualities of the Discrete Light Cone Quantization of M-theory compactified on tori, which corresponds to T-duality in the auxiliary Type II string theory. After a review of matrix theory compactification leading to noncommutative supersymmetric Yang-Mills gauge theory, I will present solutions for the fundamental and adjoint sections on a two-dimensional twisted quantum torus and generalize to three-dimensional twisted quantum tori. After showing how M-theory T-duality is realized in supersymmetric Yang-Mills gauge theories on dual noncommutative tori I will relate this to the mathematical concept of Morita equivalence of C*-algebras. As a further generalization, I consider arbitrary Ramond-Ramond backgrounds. I will also discuss the spectrum of the toroidally compactified Matrix theory corresponding to quantized electric fluxes on two and three tori. In the second part of the thesis I will present an application to conformal field theory involving quantum groups, another important example of a noncommutative space. First, I will give an introduction to Poisson-Lie groups and arrive at quantum groups using the Feynman path integral. I will quantize the symplectic leaves of the Poisson-Lie group SU(2)*. In this way we obtain the unitary representations of U q (SU(2)). I discuss the X-structure of SU(2)* and give a detailed description of its leaves using various parametrizations. Then, I will introduce a new reality structure on the Heisenberg double of Fun q (SL(N,C)) for q phase, which can be interpreted as the quantum phase space of a particle on the q-deformed mass-hyperboloid. I also present evidence that the above real form describes zero modes of certain non-compact WZNW-models
Partition function of free conformal fields in 3-plet representation
Energy Technology Data Exchange (ETDEWEB)
Beccaria, Matteo [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Università del Salento & INFN,Via Arnesano, 73100 Lecce (Italy); Tseytlin, Arkady A. [The Blackett Laboratory, Imperial College,London SW7 2AZ (United Kingdom)
2017-05-10
Simplest examples of AdS/CFT duality correspond to free CFTs in d dimensions with fields in vector or adjoint representation of an internal symmetry group dual in the large N limit to a theory of massless or massless plus massive higher spins in AdS{sub d+1}. One may also study generalizations when conformal fields belong to higher dimensional representations, i.e. carry more than two internal symmetry indices. Here we consider the case of the 3-fundamental (“3-plet”) representation. One motivation is a conjectured connection to multiple M5-brane theory: heuristic arguments suggest that it may be related to an (interacting) CFT of 6d (2,0) tensor multiplets in 3-plet representation of large N symmetry group that has an AdS{sub 7} dual. We compute the singlet partition function Z on S{sup 1}×S{sup d−1} for a free field in 3-plet representation of U(N) and analyse its novel large N behaviour. The large N limit of the low temperature expansion of Z which is convergent in the vector and adjoint cases here is only asymptotic, reflecting the much faster growth of the number of singlet operators with dimension, indicating a phase transition at very low temperature. Indeed, while the critical temperatures in the vector (T{sub c}∼N{sup γ}, γ>0) and adjoint (T{sub c}∼1) cases are finite, we find that in the 3-plet case T{sub c}∼(log N){sup −1}, i.e. it approaches zero at large N. We discuss some details of large N solution for the eigenvalue distribution. Similar conclusions apply to higher p-plet representations of U(N) or O(N) and also to the free p-tensor theories invariant under [U(N)]{sup p} or [O(N)]{sup p} with p≥3.
Superstrings, conformal field theories and holographic duality
International Nuclear Information System (INIS)
Benichou, R.
2009-06-01
The first half of this work is dedicated to the study of non-compact Gepner models.The Landau-Ginzburg description provides an easy and direct access to the geometry of the singularity associated to the non-compact Gepner models. Using these tools, we are able to give an intuitive account of the chiral rings of the models, and of the massless moduli in particular. By studying orbifolds of the singular linear dilaton models, we describe mirror pairs of non-compact Gepner models by suitably adapting the Greene-Plesser construction of mirror pairs for the compact case. For particular models, we take a large level, low curvature limit in which we can analyze corrections to a flat space orbifold approximation of the non-compact Gepner models. We have also studied bound states in N=2 Liouville theory with boundary and deep throat D-branes. We have shown that the bound states can give rise to massless vector and hyper multiplets in a low-energy gauge theory on D-branes deep inside the throat. The second half of this work deals with the issue of the quantization of the string in the presence of Ramond-Ramond backgrounds. Using the pure spinor formalism on the world-sheet, we derive the T-duality rules for all target space couplings in an efficient manner. The world-sheet path integral derivation is a proof of the equivalence of the T-dual Ramond-Ramond backgrounds which is valid non-perturbatively in the string length over the curvature radius and to all orders in perturbation theory in the string coupling. Sigma models on supergroup manifolds are relevant for quantifying string in various Anti-de-Sitter space-time with Ramond-Ramond backgrounds. We show that the conformal current algebra is realized in non-linear sigma models on supergroup manifolds with vanishing dual Coxeter number, with or without a Wess-Zumino term. The current algebra is computed. We also prove that these models realize a non-chiral Kac-Moody algebra and construct an infinite set of commuting
Conformal field theories near a boundary in general dimensions
International Nuclear Information System (INIS)
McAvity, D.M.
1995-01-01
The implications of restricted conformal invariance under conformal transformations preserving a plane boundary are discussed for general dimensions d. Calculations of the universal function of a conformal invariant ξ which appears in the two-point function of scalar operators in conformally invariant theories with a plane boundary are undertaken to first order in the ε=4-d expansion for the operator φ 2 in φ 4 theory. The form for the associated functions of ξ for the two-point functions for the basic field φ α and the auxiliary field λ in the N→∞ limit of the O(N) non-linear sigma model for any d in the range 2 α φ β and λλ. Using this method the form of the two-point function for the energy-momentum tensor in the conformal O(N) model with a plane boundary is also found. General results for the sum of the contributions of all derivative operators appearing in the operator product expansion, and also in a corresponding boundary operator expansion, to the two-point functions are also derived making essential use of conformal invariance. (orig.)
Exploring perturbative conformal field theory in Mellin space
Energy Technology Data Exchange (ETDEWEB)
Nizami, Amin A. [International Centre for Theoretical Sciences, TIFR,Hesaraghatta, Hubli, Bengaluru-560089 (India); Rudra, Arnab [Center for Quantum Mathematics and Physics (QMAP), Department of Physics,University of California, Davis, 1 Shields Ave, Davis, CA 95616 (United States); Sarkar, Sourav [Institut für Mathematik und Institut für Physik, Humboldt-Universität zu Berlin, IRIS-Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, 14476 Potsdam (Germany); Verma, Mritunjay [International Centre for Theoretical Sciences, TIFR,Hesaraghatta, Hubli, Bengaluru-560089 (India); Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad-211019 (India)
2017-01-24
We explore the Mellin representation of correlation functions in conformal field theories in the weak coupling regime. We provide a complete proof for a set of Feynman rules to write the Mellin amplitude for a general tree level Feynman diagram involving only scalar operators. We find a factorised form involving beta functions associated to the propagators, similar to tree level Feynman rules in momentum space for ordinary QFTs. We also briefly consider the case where a generic scalar perturbation of the free CFT breaks conformal invariance. Mellin space still has some utility and one can consider non-conformal Mellin representations. In this context, we find that the beta function corresponding to conformal propagator uplifts to a hypergeometric function.
Auto-optimisation for three-dimensional conformal radiotherapy of nasopharyngeal carcinoma
International Nuclear Information System (INIS)
Wu, V.W.C.; Kwong, D.W.L.; Sham, J.S.T.; Mui, A.W.L.
2003-01-01
Purpose: The purpose of this study was to evaluate the application of auto-optimisation in the treatment planning of three-dimensional conformal radiotherapy (3DCRT) of nasopharyngeal carcinoma (NPC). Methods: Twenty-nine NPC patients were planned by both forward planning and auto-optimisation methods. The forward plans, which consisted of three coplanar facial fields, were produced according to the routine planning criteria. The auto-optimised plans, which consisted of 5-15 (median 9) fields, were generated by the planning system after prescribing the dose requirements and the importance weightings of the planning target volume and organs at risk. Plans produced by the two planning methods were compared by the dose volume histogram, tumour control probability (TCP), conformity index and normal tissue complication probability (NTCP). Results: The auto-optimised plans reduced the average planner's time by over 35 min. It demonstrated better TCP and conformity index than the forward plans (P=0.03 and 0.04, respectively). Besides, the parotid gland and temporo-mandibular (TM) joint were better spared with the mean dose reduction of 31.8 and 17.7%, respectively. The slight trade off was the mild dose increase in spinal cord and brain stem with their maximum doses remaining within the tolerance limits. Conclusions: The findings demonstrated the potentials of auto-optimisation for improving target dose and parotid sparing in the 3DCRT of NPC with saving of the planner's time
Auto-optimisation for three-dimensional conformal radiotherapy of nasopharyngeal carcinoma
Energy Technology Data Exchange (ETDEWEB)
Wu, V.W.C. E-mail: orvinwu@polyu.edu.hk; Kwong, D.W.L.; Sham, J.S.T.; Mui, A.W.L
2003-08-01
Purpose: The purpose of this study was to evaluate the application of auto-optimisation in the treatment planning of three-dimensional conformal radiotherapy (3DCRT) of nasopharyngeal carcinoma (NPC). Methods: Twenty-nine NPC patients were planned by both forward planning and auto-optimisation methods. The forward plans, which consisted of three coplanar facial fields, were produced according to the routine planning criteria. The auto-optimised plans, which consisted of 5-15 (median 9) fields, were generated by the planning system after prescribing the dose requirements and the importance weightings of the planning target volume and organs at risk. Plans produced by the two planning methods were compared by the dose volume histogram, tumour control probability (TCP), conformity index and normal tissue complication probability (NTCP). Results: The auto-optimised plans reduced the average planner's time by over 35 min. It demonstrated better TCP and conformity index than the forward plans (P=0.03 and 0.04, respectively). Besides, the parotid gland and temporo-mandibular (TM) joint were better spared with the mean dose reduction of 31.8 and 17.7%, respectively. The slight trade off was the mild dose increase in spinal cord and brain stem with their maximum doses remaining within the tolerance limits. Conclusions: The findings demonstrated the potentials of auto-optimisation for improving target dose and parotid sparing in the 3DCRT of NPC with saving of the planner's time.
Three-dimensional conformal breast irradiation in the prone position
Directory of Open Access Journals (Sweden)
C. Kurtman
2003-10-01
Full Text Available The prone position can be used for the planning of adjuvant radiotherapy after conservative breast surgery in order to deliver less irradiation to lung and cardiac tissue. In the present study, we compared the results of three-dimensional conformal radiotherapy planning for five patients irradiated in the supine and prone position. Tumor stage was T1N0M0 in four patients and T1N1M0 in one. All patients had been previously submitted to conservative breast surgery. Breast size was large in three patients and moderate in the other two. Irradiation in the prone position was performed using an immobilization foam pad with a hole cut into it to accommodate the breast so that it would hang down away from the chest wall. Dose-volume histograms showed that mean irradiation doses reaching the ipsilateral lung were 8.3 ± 3.6 Gy with the patient in the supine position and 1.4 ± 1.0 Gy with the patient in the prone position (P = 0.043. The values for the contralateral lung were 1.3 ± 0.7 and 0.3 ± 0.1 Gy (P = 0.043 and the values for cardiac tissue were 4.6 ± 1.6 and 3.0 ± 1.7 Gy (P = 0.079, respectively. Thus, the dose-volume histograms demonstrated that lung tissue irradiation was significantly lower with the patient in the prone position than in the supine position. Large-breasted women appeared to benefit most from irradiation in the prone position. Prone position breast irradiation appears to be a simple and effective alternative to the conventional supine position for patients with large breasts, since they are subjected to lower pulmonary doses which may cause less pulmonary side effects in the future.
Three dimensional conformal radiation therapy in pediatric parameningeal rhabdomyosarcomas
International Nuclear Information System (INIS)
Michalski, Jeff M.; Harms, William B.; Purdy, James A.; Sur, Ranjan K.
1995-01-01
Purpose: We evaluated the utility of three dimensional (3D) treatment planning in the management of children with parameningeal head and neck rhabdomyosarcomas. Methods and Materials: Five children with parameningeal rhabdomyosarcoma were referred for treatment at our radiation oncology center from May 1990 through January 1993. Each patient was evaluated, staged, and treated according to the Intergroup Rhabdomyosarcoma Study. Patients were immobilized and underwent a computed tomography scan with contrast in the treatment position. Tumor and normal tissues were identified with assistance from a diagnostic radiologist and defined in each slice. The patients were then planned and treated with the assistance of a 3D treatment planning system. A second plan was then devised by another physician without the benefit of the 3D volumetric display. The target volumes designed with the 3D system and the two-dimensional (2D) method were then compared. The dosimetric coverage to tumor, tumor plus margin, and normal tissues was also compared with the two methods of treatment planning. Results: The apparent size of the gross tumor volume was underestimated with the conventional 2D planning method relative to the 3D method. When margin was added around the gross tumor to account for microscopic extension of disease in the 2D method, the expected area of coverage improved relative to the 3D method. In each circumstance, the minimum dose that covered the gross tumor was substantially less with the 2D method than with the 3D method. The inadequate dosimetric coverage was especially pronounced when the necessary margin to account for subclinical disease was added. In each case, the 2D plans would have delivered substantial dose to adjacent normal tissues and organs, resulting in a higher incidence of significant complications. Conclusions: 3D conformal radiation therapy has a demonstrated advantage in the treatment of sarcomas of the head and neck. The improved dosimetric coverage
Conformal invariance of the Lungren-Monin-Novikov equations for vorticity fields in 2D turbulence
Grebenev, V. N.; Wacławczyk, M.; Oberlack, M.
2017-10-01
We study the statistical properties of the vorticity field in two-dimensional turbulence. The field is described in terms of the infinite Lundgren-Monin-Novikov (LMN) chain of equations for multi-point probability density functions (pdf’s) of vorticity. We perform a Lie group analysis of the first equation in this chain using the direct method based on the canonical Lie-Bäcklund transformations devised for integro-differential equations. We analytically show that the conformal group is broken for the first LMN equation i.e. for the 1-point pdf at least for the inviscid case but the equation is still conformally invariant on the associated characteristic with zero-vorticity. Then, we demonstrate that this characteristic is conformally transformed. We find this outcome coincides with the numerical results about the conformal invariance of the statistics of zero-vorticity isolines, see e.g. Falkovich (2007 Russian Math. Surv. 63 497-510). The conformal symmetry can be understood as a ‘local scaling’ and its traces in two-dimensional turbulence were already discussed in the literature, i.e. it was conjectured more than twenty years ago in Polyakov (1993 Nucl. Phys. B 396 367-85) and clearly validated experimentally in Bernard et al (2006 Nat. Phys. 2 124-8).
Supergravity, Non-Conformal Field Theories and Brane-Worlds
Gherghetta, Tony; Gherghetta, Tony; Oz, Yaron
2002-01-01
We consider the supergravity dual descriptions of non-conformal super Yang-Mills theories realized on the world-volume of Dp-branes. We use the dual description to compute stress-energy tensor and current correlators. We apply the results to the study of dilatonic brane-worlds described by non-conformal field theories coupled to gravity. We find that brane-worlds based on D4 and D5 branes exhibit a localization of gauge and gravitational fields. We calculate the corrections to the Newton and Coulomb laws in these theories.
Globally conformal invariant gauge field theory with rational correlation functions
Nikolov, N M; Todorov, I T; CERN. Geneva; Todorov, Ivan T.
2003-01-01
Operator product expansions (OPE) for the product of a scalar field with its conjugate are presented as infinite sums of bilocal fields $V_{\\kappa} (x_1, x_2)$ of dimension $(\\kappa, \\kappa)$. For a {\\it globally conformal invariant} (GCI) theory we write down the OPE of $V_{\\kappa}$ into a series of {\\it twist} (dimension minus rank) $2\\kappa$ symmetric traceless tensor fields with coefficients computed from the (rational) 4-point function of the scalar field. We argue that the theory of a GCI hermitian scalar field ${\\cal L} (x)$ of dimension 4 in $D = 4$ Minkowski space such that the 3-point functions of a pair of ${\\cal L}$'s and a scalar field of dimension 2 or 4 vanish can be interpreted as the theory of local observables of a conformally invariant fixed point in a gauge theory with Lagrangian density ${\\cal L} (x)$.
Conformal field theory between supersymmetry and indecomposable structures
Energy Technology Data Exchange (ETDEWEB)
Eberle, H.
2006-07-15
This thesis considers conformal field theory in its supersymmetric extension as well as in its relaxation to logarithmic conformal field theory. This thesis is concerned with the subspace of K3 compactifications which is not well known yet. In particular, we inspect the intersection point of the Z{sub 2} and Z{sub 4} orbifold subvarieties within the K3 moduli space, explicitly identify the two corresponding points on the subvarieties geometrically, and give an explicit isomorphism of the three conformal field theory models located at that point, a specific Z{sub 2} and Z{sub 4} orbifold model as well as the Gepner model (2){sup 4}. We also prove the orthogonality of the two subvarieties at the intersection point. This is the starting point for the programme to investigate generic points in K3 moduli space. We use the coordinate identification at the intersection point in order to relate the coordinates of both subvarieties and to explicitly calculate a geometric geodesic between the two subvarieties as well as its generator. A generic point in K3 moduli space can be reached by such a geodesic originating at a known model. We also present advances on the conformal field theoretic side of deformations along such a geodesic using conformal deformation theory. Moreover, we regard a relaxation of conformal field theory to logarithmic conformal field theory. In particular, we study general augmented c{sub p,q} minimal models which generalise the well-known (augmented) c{sub p,1} model series. We calculate logarithmic nullvectors in both types of models. But most importantly, we investigate the low lying Virasoro representation content and fusion algebra of two general augmented c{sub p,q} models, the augmented c{sub 2,3}=0 model as well as the augmented Yang-Lee model at c{sub 2,5}=-22/5. In particular, the true vacuum representation is rather given by a rank 1 indecomposable but not irreducible subrepresentation of a rank 2 representation. We generalise these generic
Conformal field theory between supersymmetry and indecomposable structures
International Nuclear Information System (INIS)
Eberle, H.
2006-07-01
This thesis considers conformal field theory in its supersymmetric extension as well as in its relaxation to logarithmic conformal field theory. This thesis is concerned with the subspace of K3 compactifications which is not well known yet. In particular, we inspect the intersection point of the Z 2 and Z 4 orbifold subvarieties within the K3 moduli space, explicitly identify the two corresponding points on the subvarieties geometrically, and give an explicit isomorphism of the three conformal field theory models located at that point, a specific Z 2 and Z 4 orbifold model as well as the Gepner model (2) 4 . We also prove the orthogonality of the two subvarieties at the intersection point. This is the starting point for the programme to investigate generic points in K3 moduli space. We use the coordinate identification at the intersection point in order to relate the coordinates of both subvarieties and to explicitly calculate a geometric geodesic between the two subvarieties as well as its generator. A generic point in K3 moduli space can be reached by such a geodesic originating at a known model. We also present advances on the conformal field theoretic side of deformations along such a geodesic using conformal deformation theory. Moreover, we regard a relaxation of conformal field theory to logarithmic conformal field theory. In particular, we study general augmented c p,q minimal models which generalise the well-known (augmented) c p,1 model series. We calculate logarithmic nullvectors in both types of models. But most importantly, we investigate the low lying Virasoro representation content and fusion algebra of two general augmented c p,q models, the augmented c 2,3 =0 model as well as the augmented Yang-Lee model at c 2,5 =-22/5. In particular, the true vacuum representation is rather given by a rank 1 indecomposable but not irreducible subrepresentation of a rank 2 representation. We generalise these generic examples to give the representation content and
Two-dimensional fractal geometry, critical phenomena and conformal invariance
International Nuclear Information System (INIS)
Duplantier, B.
1988-01-01
The universal properties of critical geometrical systems in two-dimensions (2D) like the O (n) and Potts models, are described in the framework of Coulomb gas methods and conformal invariance. The conformal spectrum of geometrical critical systems obtained is made of a discrete infinite series of scaling dimensions. Specific applications involve the fractal properties of self-avoiding walks, percolation clusters, and also some non trivial critical exponents or fractal dimensions associated with subsets of the planar Brownian motion. The statistical mechanics of the same critical models on a random 2D lattice (namely in presence of a critically-fluctuating metric, in the so-called 2D quantum gravity) is also addressed, and the above critical geometrical systems are shown to be exactly solvable in this case. The new ''gravitational'' conformal spectrum so derived is found to satisfy the recent Knizhnik, Polyakov and Zamolodchikov quadratic relation which links it to the standard conformal spectrum in the plane
Irreversibility and higher-spin conformal field theory
Anselmi, D
2000-01-01
I discuss the idea that quantum irreversibility is a general principle of nature and a related "conformal hypothesis", stating that all fundamental quantum field theories should be renormalization-group (RG) interpolations between ultraviolet and infrared conformal fixed points. In particular, the Newton constant should be viewed as a low-energy effect of the RG scale. This approach leads naturally to consider higher-spin conformal field theories, which are here classified, as candidate high-energy theories. Bosonic conformal tensors have a positive-definite action, equal to the square of a field strength, and a higher-derivative gauge invariance. The central charges c and a are well defined and positive. I calculate their values and study the operator-product structure. Fermionic theories have no gauge invariance and can be coupled to Abelian and non-Abelian gauge fields in a renormalizable way. At the quantum level, they contribute to the one-loop beta function with the same sign as ordinary matter, admit a...
A conformal field theory description of fractional quantum Hall states
Ardonne, E.
2002-01-01
In this thesis, we give a description of fractional quantum Hall states in terms of conformal field theory (CFT). As was known for a long time, the Laughlin states could be written in terms of correlators of chiral vertex operators of a c=1 CFT. It was shown by G. Moore and N. Read that more general
Introduction to conformal field theory and string theory
International Nuclear Information System (INIS)
Dixon, L.J.
1989-12-01
These lectures are meant to provide a brief introduction to conformal field theory (CFT) and string theory for those with no prior exposure to the subjects. There are many excellent reviews already available, and most of these go in to much more detail than I will be able to here. 52 refs., 11 figs
Intensity-modulated three-dimensional conformal radiotherapy
International Nuclear Information System (INIS)
Mohan, Radhe
1996-01-01
Optimized intensity-modulated treatments one of the important advances in photon radiotherapy. Intensity modulation provides a greatly increased control over dose distributions. Such control can be maximally exploited to achieve significantly higher levels of conformation to the desired clinical objectives using sophisticated optimization techniques. Safe, rapid and efficient delivery of intensity-modulated treatments has become feasible using a dynamic multi-leaf collimator under computer control. The need for all other field shaping devices such as blocks, wedges and compensators is eliminated. Planning and delivery of intensity-modulated treatments is amenable to automation and development of class solutions for each treatment site and stage which can be implemented not only at major academic centers but on a wide scale. A typical treatment involving as many as 10 fields can be delivered in times shorter than much simpler conventional treatments. The main objective of the course is to give an overview of the current state of the art of planning and delivery methods of intensity-modulated treatments. Specifically, the following topics will be covered using representative optimized plans and treatments: 1. A typical procedure for planning and delivering an intensity-modulated treatment. 2. Quantitative definition of criteria (i.e., the objective function) of optimization of intensity-modulated treatments. Clinical relevance of objectives and the dependence of the quality of optimized intensity-modulated plans upon whether the objectives are stated purely in terms of simple dose or dose-volume criteria or whether they incorporate biological indices. 3. Importance of the lateral transport of radiation in the design of intensity-modulated treatments. Impact on dose homogeneity and the optimum choice of margins. 4. Use of intensity-modulated treatments in escalation of tumor dose for the same or lower normal tissue dose. Fractionation of intensity-modulated treatments
Intensity-modulated three-dimensional conformal radiotherapy
International Nuclear Information System (INIS)
Mohan, Radhe
1997-01-01
Optimized intensity-modulated treatments one of the important advances in photon radiotherapy. Intensity modulation provides a greatly increased control over dose distributions. Such control can be maximally exploited to achieve significantly higher levels of conformation to the desired clinical objectives using sophisticated optimization techniques. Safe, rapid and efficient delivery of intensity-modulated treatments has become feasible using a dynamic multi-leaf collimator under computer control. The need for all other field shaping devices such as blocks, wedges and compensators is eliminated. Planning and delivery of intensity-modulated treatments is amenable to automation and development of class solutions for each treatment site and stage which can be implemented not only at major academic centers but on a wide scale. A typical treatment involving as many as 10 fields can be delivered in times shorter than much simpler conventional treatments. The main objective of the course is to give an overview of the current state of the art of planning and delivery methods of intensity-modulated treatments. Specifically, the following topics will be covered using representative optimized plans and treatments: 1. A typical procedure for planning and delivering an intensity-modulated treatment. 2. Quantitative definition of criteria (i.e., the objective function) of optimization of intensity-modulated treatments. Clinical relevance of objectives and the dependence of the quality of optimized intensity-modulated plans upon whether the objectives are stated purely in terms of simple dose or dose-volume criteria or whether they incorporate biological indices. 3. Importance of the lateral transport of radiation in the design of intensity-modulated treatments. Impact on dose homogeneity and the optimum choice of margins. 4. Use of intensity-modulated treatments in escalation of tumor dose for the same or lower normal tissue dose. Fractionation of intensity-modulated treatments
Hawking radiation of five-dimensional charged black holes with scalar fields
Directory of Open Access Journals (Sweden)
Yan-Gang Miao
2017-09-01
Full Text Available We investigate the Hawking radiation cascade from the five-dimensional charged black hole with a scalar field coupled to higher-order Euler densities in a conformally invariant manner. We give the semi-analytic calculation of greybody factors for the Hawking radiation. Our analysis shows that the Hawking radiation cascade from this five-dimensional black hole is extremely sparse. The charge enhances the sparsity of the Hawking radiation, while the conformally coupled scalar field reduces this sparsity.
The quantum symmetry of rational conformal field theories
Directory of Open Access Journals (Sweden)
César Gómez
1991-04-01
Full Text Available The quantum group symmetry of the c ˇ1 Rational Conformal Field Theory, in its Coulomb gas version, is formulated in terms of a new type of screened vertex operators, which define the representation spaces of a quantum group Q. The conformal properties of these operators show a deep interplay between the quantum group Q and the Virasoro algebra.The R-matrix, the comultiplication rules and the quantum Clebsch-Gordan coefficients of Q are obtained using contour deformation techniques. Finally, the relation between the chiral vertex operators and the quantum Clebsch-Gordan coefficients is shown.
The Toda lattice hierarchy and deformation of conformal field theories
International Nuclear Information System (INIS)
Fukuma, M.
1990-01-01
In this paper, the authors point out that the Toda lattice hierarchy known in soliton theory is relevant for the description of the deformations of conformal field theories while the KP hierarchy describes unperturbed conformal theories. It is shown that the holomorphic parts of the conserved currents in the perturbed system (the Toda lattice hierarchy) coincide with the conserved currents in the KP hierarchy and can be written in terms of the W-algebraic currents. Furthermore, their anti-holomorphic counterparts are obtained
Effect of External Electric Field Stress on Gliadin Protein Conformation
Singh, Ashutosh; Munshi, Shirin; Raghavan, Vijaya
2013-01-01
A molecular dynamic (MD) modeling approach was applied to evaluate the effect of external electric field on gliadin protein structure and surface properties. Static electric field strengths of 0.001 V/nm and 0.002 V/nm induced conformational changes in the protein but had no significant effect on its surface properties. The study of hydrogen bond evolution during the course of simulation revealed that the root mean square deviation, radius of gyration and secondary structure formation, all de...
On osp(2|2) conformal field theories
International Nuclear Information System (INIS)
Ding Xiangmao; Gould, Mark D; Mewton, Courtney J; Zhang Yaozhong
2003-01-01
We study the conformal field theories corresponding to current superalgebras osp(2|2) (1) k and osp(2|2) (2) k . We construct the free field realizations, screen currents and primary fields of these current superalgebras at general level k. All the results for osp(2|2) (2) k are new, and the results for the primary fields of osp(2|2) (1) k also seem to be new. Our results are expected to be useful in the supersymmetric approach to Gaussian disordered systems such as the random bond Ising model and the Dirac model
Conformal consistency relations for single-field inflation
International Nuclear Information System (INIS)
Creminelli, Paolo; Noreña, Jorge; Simonović, Marko
2012-01-01
We generalize the single-field consistency relations to capture not only the leading term in the squeezed limit — going as 1/q 3 , where q is the small wavevector — but also the subleading one, going as 1/q 2 . This term, for an (n+1)-point function, is fixed in terms of the variation of the n-point function under a special conformal transformation; this parallels the fact that the 1/q 3 term is related with the scale dependence of the n-point function. For the squeezed limit of the 3-point function, this conformal consistency relation implies that there are no terms going as 1/q 2 . We verify that the squeezed limit of the 4-point function is related to the conformal variation of the 3-point function both in the case of canonical slow-roll inflation and in models with reduced speed of sound. In the second case the conformal consistency conditions capture, at the level of observables, the relation among operators induced by the non-linear realization of Lorentz invariance in the Lagrangian. These results mean that, in any single-field model, primordial correlation functions of ζ are endowed with an SO(4,1) symmetry, with dilations and special conformal transformations non-linearly realized by ζ. We also verify the conformal consistency relations for any n-point function in models with a modulation of the inflaton potential, where the scale dependence is not negligible. Finally, we generalize (some of) the consistency relations involving tensors and soft internal momenta
The value of 18F-FDG PET in three-dimensional conformal radiotherapy of cancer
International Nuclear Information System (INIS)
Lv Huiqing; Zhang Zhongmin; Lv Zhonghong
2006-01-01
Three-dimensional conformal radiotherapy (3D-CRT) is based on an extensive use of modern medical imaging techniques. Delineation of the gross tumor volume and organs at risk constitutes one of the most important phases of conformal radiotherapy procedures. 18 F-fluorodeoxyglucose ( 18 F-FDG) PET possesses greater sensitivity and accuracy in detecting diseased lymph nodes, is an important staging examination for patients considered for radiation treatment with curative intent. 18 F-FDG PET has an important role in delineation of gross tumor volume for patients treated with three-dimensional conformal radiotherapy. (authors)
Conformally covariant massless spin-two field equations
International Nuclear Information System (INIS)
Drew, M.S.; Gegenberg, J.D.
1980-01-01
An explicit proof is constructed to show that the field equations for a symmetric tensor field hsub(ab) describing massless spin-2 particles in Minkowski space-time are not covariant under the 15-parameter group SOsub(4,2); this group is usually associated with conformal transformations on flat space, and here it will be considered as a global gauge group which acts upon matter fields defined on space-time. Notwithstanding the above noncovariance, the equations governing the rank-4 tensor Ssub(abcd) constructed from hsub(ab) are shown to be covariant provided the contraction Ssub(ab) vanishes. Conformal covariance is proved by demonstrating the covariance of the equations for the equivalent 5-component complex field; in fact, covariance is proved for a general field equation applicable to massless particles of any spin >0. It is shown that the noncovariance of the hsub(ab) equations may be ascribed to the fact that the transformation behaviour of hsub(ab) is not the same as that of a field consisting of a gauge only. Since this is in contradistinction to the situation for the electromagnetic-field equations, the vector form of the electromagnetic equations is cast into a form which can be duplicated for the hsub(ab)-field. This procedure results in an alternative, covariant, field equation for hsub(ab). (author)
Sewing constraints for conformal field theories on surfaces with boundaries
International Nuclear Information System (INIS)
Lewellen, D.C.
1992-01-01
In a conformal field theory, correlation functions on any Riemann surface are in principle unambiguously defined by sewing together three-point functions on the sphere, provided that the four-point functions on the sphere are crossing symmetric, and the one-point functions on the torus are modular covariant. In this work we extend Sonoda's proof of this result to conformal field theories defined on surfaces with boundaries. Four additional sewing constraints arise; three on the half-plane and one on the cylinder. These relate the various OPE coefficients in the theory (bulk, boundary, and bulk-boundary) to one another. In rational theories these relations can be expressed in terms of data arising solely within the bulk theory: The matrix S which implements modular transformations on the characters, and the matrices implementing duality transformations on the four-point conformal-block functions. As an example we solve these relations for the boundary and bulk-boundary structure constants in the Ising model with all possible conformally invariant boundary conditions. The role of the basic sewing constraints in the construction of open string theories is discussed. (orig.)
Optimized dose conformation of multi-leaf collimator fields
International Nuclear Information System (INIS)
Serago, Christopher F.; Buskirk, Steven J.; Foo, May L.; McLaughlin, Mark P.
1996-01-01
Purpose/Objective: Current commercially available multi-leaf collimators (MLC) have leaf widths of about 1 cm. These leaf widths may produce stepped dose gradients at the fields edges at the 50% dose level. Small local perturbations of the dose distribution from the prescribed/expected dose distribution may not be acceptable for some clinical applications. Improvements to the conformation of the MLC dose distribution may be achieved using multiple exposures per MLC field, with either shifting the table/patient position, or rotating the orientation of the MLC jaws between exposures. Material and Methods: Dose distributions for MLC, primary jaws only, and lead alloy block fields were measured with film dosimetry for 6 and 20 MV photon beams in a solid water phantom. Square, circular, and typical clinical prostate, brain, lung, esophagus, and head and neck fields were measured. MLC field shapes were produced using a commercial MLC with a leaf width of 1 cm at the treatment isocenter. The dose per MLC field was delivered in either single (conventional) or multiple exposures. The table(patient) position or the collimator rotation was shifted between exposures when multiple exposure MLC fields were used. Differences in the dose distribution were evaluated at the 90% and 50% isodose level. Displacements of the measured 50% isodose from the prescribed/expected 50% isodose were measured at 5 degree intervals. Results: Measurements of the penumbra at a 10 cm depth for square fields show that using double exposure MLC fields with .5 cm table index decreases the effective penumbra by 1 mm. For clinical shaped fields, displacements between the prescribed/expected 50% isodose and the measured 50% isodose for conventional single exposure MLC fields are measured to be as great as 9 mm, and discrepancies on the order of 5 to 6 mm are common. In contrast, the maximum displacement errors measured with multiple exposure MLC fields are less than 5 mm and rarely more than 4 mm. In some
Minimal Representations and Reductive Dual Pairs in Conformal Field Theory
International Nuclear Information System (INIS)
Todorov, Ivan
2010-01-01
A minimal representation of a simple non-compact Lie group is obtained by 'quantizing' the minimal nilpotent coadjoint orbit of its Lie algebra. It provides context for Roger Howe's notion of a reductive dual pair encountered recently in the description of global gauge symmetry of a (4-dimensional) conformal observable algebra. We give a pedagogical introduction to these notions and point out that physicists have been using both minimal representations and dual pairs without naming them and hence stand a chance to understand their theory and to profit from it.
Radiation from a moving mirror in two dimensional space-time: conformal anomaly
International Nuclear Information System (INIS)
Fulling, S.A.; Davies, P.C.W.
1976-01-01
The energy-momentum tensor is calculated in the two dimensional quantum theory of a massless scalar field influenced by the motion of a perfectly reflecting boundary (mirror). The simple model system evidently can provide insight into more sophisticated processes, such as particle production in cosmological models and exploding black holes. In spite of the conformally static nature of the problem, the vacuum expectation value of the tensor for an arbitrary mirror trajectory exhibits a non-vanishing radiation flux (which may be readily computed). The expectation value of the instantaneous energy flux is negative when the proper acceleration of the mirror is increasing, but the total energy radiated during a bounded mirror motion is positive. A uniformly accelerating mirror does not radiate; however, the quantization does not coincide with the treatment of that system as a 'static universe'. The calculation of the expectation value requires a regularization procedure of covariant separation of points (in products of field operators) along time-like geodesics; more naive methods do not yield the same answers. A striking example involving two mirrors clarifies the significance of the conformal anomaly. (author)
Mixed-symmetry fields in AdS(5), conformal fields, and AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, Moscow 119991 (Russian Federation)
2015-01-15
Mixed-symmetry arbitrary spin massive, massless, and self-dual massive fields in AdS(5) are studied. Light-cone gauge actions for such fields leading to decoupled equations of motion are constructed. Light-cone gauge formulation of mixed-symmetry anomalous conformal currents and shadows in 4d flat space is also developed. AdS/CFT correspondence for normalizable and non-normalizable modes of mixed-symmetry AdS fields and the respective boundary mixed-symmetry anomalous conformal currents and shadows is studied. We demonstrate that the light-cone gauge action for massive mixed-symmetry AdS field evaluated on solution of the Dirichlet problem amounts to the light-cone gauge 2-point vertex of mixed-symmetry anomalous shadow. Also we show that UV divergence of the action for mixed-symmetry massive AdS field with some particular value of mass parameter evaluated on the Dirichlet problem amounts to the action of long mixed-symmetry conformal field, while UV divergence of the action for mixed-symmetry massless AdS field evaluated on the Dirichlet problem amounts to the action of short mixed-symmetry conformal field. We speculate on string theory interpretation of a model which involves short low-spin conformal fields and long higher-spin conformal fields.
International Nuclear Information System (INIS)
Setare, M R; Kamali, V
2011-01-01
We show that a BTZ black hole solution of cosmological topological massive gravity has a hidden conformal symmetry. In this regard, we consider the wave equation of a massless scalar field propagating in BTZ spacetime and find that the wave equation could be written in terms of the SL(2, R) quadratic Casimir. From the conformal coordinates, the temperatures of the dual conformal field theories (CFTs) could be read directly. Moreover, we compute the microscopic entropy of the dual CFT by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole. Then, we consider Galilean conformal algebras (GCA), which arises as a contraction of relativistic conformal algebras (x → εx, t → t, ε → 0). We show that there is a correspondence between GCA 2 on the boundary and contracted BTZ in the bulk. For this purpose we obtain the central charges and temperatures of GCA 2 . Then, we compute the microscopic entropy of the GCA 2 by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole in a non-relativistic limit. The absorption cross section of a near-region scalar field also matches the microscopic absorption cross section of the dual GCA 2 . So we find further evidence that shows correspondence between a contracted BTZ black hole and two-dimensional GCA.
Higher Curvature Gravity from Entanglement in Conformal Field Theories
Haehl, Felix M.; Hijano, Eliot; Parrikar, Onkar; Rabideau, Charles
2018-05-01
By generalizing different recent works to the context of higher curvature gravity, we provide a unifying framework for three related results: (i) If an asymptotically anti-de Sitter (AdS) spacetime computes the entanglement entropies of ball-shaped regions in a conformal field theory using a generalized Ryu-Takayanagi formula up to second order in state deformations around the vacuum, then the spacetime satisfies the correct gravitational equations of motion up to second order around the AdS background. (ii) The holographic dual of entanglement entropy in higher curvature theories of gravity is given by the Wald entropy plus a particular correction term involving extrinsic curvatures. (iii) Conformal field theory relative entropy is dual to gravitational canonical energy (also in higher curvature theories of gravity). Especially for the second point, our novel derivation of this previously known statement does not involve the Euclidean replica trick.
Towers of algebras in rational conformal field theories
International Nuclear Information System (INIS)
Gomez, C.; Sierra, G.
1991-01-01
This paper reports on Jones fundamental construction applied to rational conformal field theories. The Jones algebra which emerges in this application is realized in terms of duality operations. The generators of the algebra are an open version of Verlinde's operators. The polynomial equations appear in this context as sufficient conditions for the existence of Jones algebra. The ADE classification of modular invariant partition functions is put in correspondence with Jones classification of subfactors
Relating the archetypes of logarithmic conformal field theory
International Nuclear Information System (INIS)
Creutzig, Thomas; Ridout, David
2013-01-01
Logarithmic conformal field theory is a rich and vibrant area of modern mathematical physics with well-known applications to both condensed matter theory and string theory. Our limited understanding of these theories is based upon detailed studies of various examples that one may regard as archetypal. These include the c=−2 triplet model, the Wess–Zumino–Witten model on SL(2;R) at level k=−1/2 , and its supergroup analogue on GL(1|1). Here, the latter model is studied algebraically through representation theory, fusion and modular invariance, facilitating a subsequent investigation of its cosets and extended algebras. The results show that the archetypes of logarithmic conformal field theory are in fact all very closely related, as are many other examples including, in particular, the SL(2|1) models at levels 1 and −1/2 . The conclusion is then that the archetypal examples of logarithmic conformal field theory are practically all the same, so we should not expect that their features are in any way generic. Further archetypal examples must be sought
Relating the archetypes of logarithmic conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Creutzig, Thomas, E-mail: tcreutzig@mathematik.tu-darmstadt.de [Department of Physics and Astronomy, University of North Carolina, Phillips Hall, CB 3255, Chapel Hill, NC 27599-3255 (United States); Fachbereich Mathematik, Technische Universität Darmstadt, Schloßgartenstraße 7, 64289 Darmstadt (Germany); Ridout, David, E-mail: david.ridout@anu.edu.au [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Mathematical Sciences Institute, Australian National University, Canberra, ACT 0200 (Australia)
2013-07-21
Logarithmic conformal field theory is a rich and vibrant area of modern mathematical physics with well-known applications to both condensed matter theory and string theory. Our limited understanding of these theories is based upon detailed studies of various examples that one may regard as archetypal. These include the c=−2 triplet model, the Wess–Zumino–Witten model on SL(2;R) at level k=−1/2 , and its supergroup analogue on GL(1|1). Here, the latter model is studied algebraically through representation theory, fusion and modular invariance, facilitating a subsequent investigation of its cosets and extended algebras. The results show that the archetypes of logarithmic conformal field theory are in fact all very closely related, as are many other examples including, in particular, the SL(2|1) models at levels 1 and −1/2 . The conclusion is then that the archetypal examples of logarithmic conformal field theory are practically all the same, so we should not expect that their features are in any way generic. Further archetypal examples must be sought.
Conformal coupling of gravitational wave field to curvature
International Nuclear Information System (INIS)
Grishchuk, L.P.; Yudin, V.
1980-01-01
Conformal properties of the equations for weak gravitational waves in a curved space--time are investigated. The basic equations are derived in the linear approximation from Einstein's equations. They represent, in fact, the equations for the second-rank tensor field h/sub alphabeta/, restricted by the auxiliary conditions h/sub α//sup β//sub ;/α =0, hequivalentγ/sub alphabeta/h/sup alphabeta/=0, and embedded into the background space--time with the metric tensor γ/sub alphabeta/. It is shown that the equations for h/sub alphabeta/ are not conformally invariant under the transformations gamma-circumflex/sub alphabeta/ =e/sup 2sigma/γ/sub alphabeta/ and h/sub alphabeta/ =e/sup sigma/h/sub alphabeta/, except for those metric rescalings which transform the Ricci scalar R of the original background space--time into e/sup -2sigma/R, where R is the Ricci scalar of the conformally related background space--time. The general form of the equations for h/sub alphabeta/ which are conformally invariant have been deduced. It is shown that these equations cannot be derived in the linear approximation from any tensor equations which generalize the Einstein equations
Energy flow in non-equilibrium conformal field theory
Bernard, Denis; Doyon, Benjamin
2012-09-01
We study the energy current and its fluctuations in quantum gapless 1d systems far from equilibrium modeled by conformal field theory, where two separated halves are prepared at distinct temperatures and glued together at a point contact. We prove that these systems converge towards steady states, and give a general description of such non-equilibrium steady states in terms of quantum field theory data. We compute the large deviation function, also called the full counting statistics, of energy transfer through the contact. These are universal and satisfy fluctuation relations. We provide a simple representation of these quantum fluctuations in terms of classical Poisson processes whose intensities are proportional to Boltzmann weights.
Conformal conservation laws for second-order scalar fields
International Nuclear Information System (INIS)
Blakeskee, J.S.; Logan, J.D.
1976-01-01
It is considered an action integral over space-time whose Lagrangian depends upon a scalar field an upon derivatives of the field function up to second order. From invariance identities obtained by the authors in an earlier work it is shown how a new proof of Noether's theorem for this second-order problem follows in the multiple integral case. Finally, conservation laws are written down in the case that the given action integral be invariant under the fifteen-parameter special conformal group
Black Hole Entropy from Conformal Field Theory in Any Dimension
International Nuclear Information System (INIS)
Carlip, S.
1999-01-01
Restricted to a black hole horizon, the open-quotes gaugeclose quotes algebra of surface deformations in general relativity contains a Virasoro subalgebra with a calculable central charge. The fields in any quantum theory of gravity must transform accordingly, i.e., they must admit a conformal field theory description. Applying Cardy close-quote s formula for the asymptotic density of states, I use this result to derive the Bekenstein-Hawking entropy. This method is universal it holds for any black hole, and requires no details of quantum gravity but it is also explicitly statistical mechanical, based on counting microscopic states. copyright 1999 The American Physical Society
Two-dimensional NMR investigations of the dynamic conformations of phospholipids and liquid crystals
Energy Technology Data Exchange (ETDEWEB)
Hong, Mei [Univ. of California, Berkeley, CA (United States). Applied Science and Technology
1996-05-01
Two-dimensional 13C, 1H, and 31P nuclear magnetic resonance (NMR) techniques are developed and used to study molecular structure and dynamics in liquid-crystalline systems, primarily phospholipids and nematic liquid crystals. NMR spectroscopy characterizes molecular conformation in terms of orientations and distances of molecular segments. In anisotropically mobile systems, this is achieved by measuring motionally-averaged nuclear dipolar couplings and chemical shift anisotropies. The short-range couplings yield useful bond order parameters, while the long-range interactions constrain the overall conformation. In this work, techniques for probing proton dipolar local fields are further developed to obtain highlyresolved dipolar couplings between protons and rare spins. By exploiting variable-angle sample spinning techniques, orientation-sensitive NMR spectra are resolved according to sitespecific isotropic chemical shifts. Moreover, the signs and magnitudes of various short-range dipolar couplings are obtained. They are used in novel theoretical analyses that provide information about segmental orientations and their distributions. Such information is obtained in a model-independent fashion or with physically reasonable assumptions. The structural investigation of phospholipids is focused on the dynam
The unitary conformal field theory behind 2D Asymptotic Safety
Energy Technology Data Exchange (ETDEWEB)
Nink, Andreas; Reuter, Martin [Institute of Physics, PRISMA & MITP, Johannes Gutenberg University Mainz,Staudingerweg 7, D-55099 Mainz (Germany)
2016-02-25
Being interested in the compatibility of Asymptotic Safety with Hilbert space positivity (unitarity), we consider a local truncation of the functional RG flow which describes quantum gravity in d>2 dimensions and construct its limit of exactly two dimensions. We find that in this limit the flow displays a nontrivial fixed point whose effective average action is a non-local functional of the metric. Its pure gravity sector is shown to correspond to a unitary conformal field theory with positive central charge c=25. Representing the fixed point CFT by a Liouville theory in the conformal gauge, we investigate its general properties and their implications for the Asymptotic Safety program. In particular, we discuss its field parametrization dependence and argue that there might exist more than one universality class of metric gravity theories in two dimensions. Furthermore, studying the gravitational dressing in 2D asymptotically safe gravity coupled to conformal matter we uncover a mechanism which leads to a complete quenching of the a priori expected Knizhnik-Polyakov-Zamolodchikov (KPZ) scaling. A possible connection of this prediction to Monte Carlo results obtained in the discrete approach to 2D quantum gravity based upon causal dynamical triangulations is mentioned. Similarities of the fixed point theory to, and differences from, non-critical string theory are also described. On the technical side, we provide a detailed analysis of an intriguing connection between the Einstein-Hilbert action in d>2 dimensions and Polyakov’s induced gravity action in two dimensions.
Fitting of hadron spectrum in 5-dimensional conformal relativity
International Nuclear Information System (INIS)
Luna-Acosta, G.A.
1984-11-01
There is no well known kinematic theory of masses which can be used to compute masses of observed particles. The theory of mass of Conformal Relativity in 5-dimensions does promise to fulfill this need. Here we apply its theoretical results to hadrons and successfully fit their masses with a universal length l (the size of the 5th dimension) of 1.36 Fermi. Our fitting scheme shows a trend from which we can predict the observed masses. We conjecture about reasons our fitting distinguishes between hadrons in terms of their quark composition. The value of l suggests physical interpretations and possible means of detection. (author)
Associative-algebraic approach to logarithmic conformal field theories
International Nuclear Information System (INIS)
Read, N.; Saleur, Hubert
2007-01-01
We set up a strategy for studying large families of logarithmic conformal field theories by using the enlarged symmetries and non-semisimple associative algebras appearing in their lattice regularizations (as discussed in a companion paper [N. Read, H. Saleur, Enlarged symmetry algebras of spin chains, loop models, and S-matrices, cond-mat/0701259]). Here we work out in detail two examples of theories derived as the continuum limit of XXZ spin-1/2 chains, which are related to spin chains with supersymmetry algebras gl(n|n) and gl(n+1 vertical bar n), respectively, with open (or free) boundary conditions in all cases. These theories can also be viewed as vertex models, or as loop models. Their continuum limits are boundary conformal field theories (CFTs) with central charge c=-2 and c=0 respectively, and in the loop interpretation they describe dense polymers and the boundaries of critical percolation clusters, respectively. We also discuss the case of dilute (critical) polymers as another boundary CFT with c=0. Within the supersymmetric formulations, these boundary CFTs describe the fixed points of certain nonlinear sigma models that have a supercoset space as the target manifold, and of Landau-Ginzburg field theories. The submodule structures of indecomposable representations of the Virasoro algebra appearing in the boundary CFT, representing local fields, are derived from the lattice. A central result is the derivation of the fusion rules for these fields
Supersymmetric gauge theories, quantization of Mflat, and conformal field theory
International Nuclear Information System (INIS)
Teschner, J.; Vartanov, G.S.
2013-02-01
We propose a derivation of the correspondence between certain gauge theories with N=2 supersymmetry and conformal field theory discovered by Alday, Gaiotto and Tachikawa in the spirit of Seiberg-Witten theory. Based on certain results from the literature we argue that the quantum theory of the moduli spaces of flat SL(2,R)-connections represents a nonperturbative ''skeleton'' of the gauge theory, protected by supersymmetry. It follows that instanton partition functions can be characterized as solutions to a Riemann-Hilbert type problem. In order to solve it, we describe the quantization of the moduli spaces of flat connections explicitly in terms of two natural sets of Darboux coordinates. The kernel describing the relation between the two pictures represents the solution to the Riemann Hilbert problem, and is naturally identified with the Liouville conformal blocks.
International Nuclear Information System (INIS)
Liang Feng; Lu Zhonghong; Yao Zhijun; Cao Yongzhen
2011-01-01
Objective: To observe the therapeutic effect of three-dimensional conformal radiation therapy (3DCRT) for nasopharyngeal carcinoma (NPC). Methods: 78 patients with NPC was treated by radiation schedule in two phases. In the first phase, nasopharyngeal lesions and metastases of all patients were treated by three-dimensional conformal radiation therapy (3DCRT) with a fraction of 2-5 Gy daily, 5 day per weeks, total dose 30 Gy. The second phase T1N0 or parts of T2N0 patients were done by Conventional radiotherapy with total dose 55 Gy on two small lateral opposing fields + with total dose 50 Gy on neck on tangential field,adding a 3 cm block. Patients with lymph node metastasis were given 55 Gy on the dacio-neck field (After 40 Gy, two small lateral opposing fields were used to boost the primary tumor while the spinal cord shielded) + with total dose 55 Gy on lower neck on tangential field. The upper bound of designed therapeutic field was set to connect with lower bound of main therapeutic field. Results: Three months after treatment,the rate of CR, PR, SD, PD were 38.5%, 55.1%, 5.1%, 1.3%, Total effective rate (CR+PR) were 93.6%. The 1-year, 2-year, 3-year and 5-year local-regional control rates were 92.3%, 88.5%, 78.2%, 70.5%.The 1-year, 2-year , 3-year and 5-year overall survival rate were 96.2%, 89.7%, 83.3%, 71.8%. Appearing early radiation response is well tolerated and no obviously mouth difficulties and cranial nerve damage observed. Conclusion: Clinical result of early-course three-dimensional conformal radiation therapy (3DCRT) for nasopharyngeal carcinoma (NPC) is good. (authors)
On conformal Paneitz curvature equations in higher dimensional spheres
International Nuclear Information System (INIS)
El Mehdi, Khalil
2004-11-01
We study the problem of prescribing the Paneitz curvature on higher dimensional spheres. Particular attention is paid to the blow-up points, i.e. the critical points at infinity of the corresponding variational problem. Using topological tools and a careful analysis of the gradient flow lines in the neighborhood of such critical points at infinity, we prove some existence results. (author)
Stochastic geometry of critical curves, Schramm-Loewner evolutions and conformal field theory
International Nuclear Information System (INIS)
Gruzberg, Ilya A
2006-01-01
Conformally invariant curves that appear at critical points in two-dimensional statistical mechanics systems and their fractal geometry have received a lot of attention in recent years. On the one hand, Schramm (2000 Israel J. Math. 118 221 (Preprint math.PR/9904022)) has invented a new rigorous as well as practical calculational approach to critical curves, based on a beautiful unification of conformal maps and stochastic processes, and by now known as Schramm-Loewner evolution (SLE). On the other hand, Duplantier (2000 Phys. Rev. Lett. 84 1363; Fractal Geometry and Applications: A Jubilee of Benot Mandelbrot: Part 2 (Proc. Symp. Pure Math. vol 72) (Providence, RI: American Mathematical Society) p 365 (Preprint math-ph/0303034)) has applied boundary quantum gravity methods to calculate exact multifractal exponents associated with critical curves. In the first part of this paper, I provide a pedagogical introduction to SLE. I present mathematical facts from the theory of conformal maps and stochastic processes related to SLE. Then I review basic properties of SLE and provide practical derivation of various interesting quantities related to critical curves, including fractal dimensions and crossing probabilities. The second part of the paper is devoted to a way of describing critical curves using boundary conformal field theory (CFT) in the so-called Coulomb gas formalism. This description provides an alternative (to quantum gravity) way of obtaining the multifractal spectrum of critical curves using only traditional methods of CFT based on free bosonic fields
Conformal fields. From Riemann surfaces to integrable hierarchies
International Nuclear Information System (INIS)
Semikhatov, A.M.
1991-01-01
I discuss the idea of translating ingredients of conformal field theory into the language of hierarchies of integrable differential equations. Primary conformal fields are mapped into (differential or matrix) operators living on the phase space of the hierarchy, whereas operator insertions of, e.g., a current or the energy-momentum tensor, become certain vector fields on the phase space and thus acquire a meaning independent of a given Riemann surface. A number of similarities are observed between the structures arising on the hierarchy and those of the theory on the world-sheet. In particular, there is an analogue of the operator product algebra with the Cauchy kernel replaced by its 'off-shell' hierarchy version. Also, hierarchy analogues of certain operator insertions admit two (equivalent, but distinct) forms, resembling the 'bosonized' and 'fermionized' versions respectively. As an application, I obtain a useful reformulation of the Virasoro constraints of the type that arise in matrix models, as a system of equations on dressing (or Lax) operators (rather than correlation functions, i.e., residues or traces). This also suggests an interpretation in terms of a 2D topological field theory, which might be extended to a correspondence between Virasoro-constrained hierarchies and topological theories. (orig.)
International Nuclear Information System (INIS)
Hamilton, Russell J.; Kuchnir, Franca T.; Sweeney, Patrick; Rubin, Steven J.; Dujovny, Manuel; Pelizzari, Charles A.; Chen, George T. Y.
1995-01-01
Purpose: Compare the use of static conformal fields with the use of multiple noncoplanar arcs for stereotactic radiosurgery or stereotactic radiotherapy treatment of intracranial lesions. Evaluate the efficacy of these treatment techniques to deliver dose distributions comparable to those considered acceptable in current radiotherapy practice. Methods and Materials: A previously treated radiosurgery case of a patient presenting with an irregularly shaped intracranial lesion was selected. Using a three-dimensional (3D) treatment-planning system, treatment plans using a single isocenter multiple noncoplanar arc technique and multiple noncoplanar conformal static fields were generated. Isodose distributions and dose volume histograms (DVHs) were computed for each treatment plan. We required that the 80% (of maximum dose) isodose surface enclose the target volume for all treatment plans. The prescription isodose was set equal to the minimum target isodose. The DVHs were analyzed to evaluate and compare the different treatment plans. Results: The dose distribution in the target volume becomes more uniform as the number of conformal fields increases. The volume of normal tissue receiving low doses (> 10% of prescription isodose) increases as the number of static fields increases. The single isocenter multiple arc plan treats the greatest volume of normal tissue to low doses, approximately 1.6 times more volume than that treated by four static fields. The volume of normal tissue receiving high (> 90% of prescription isodose) and intermediate (> 50% of prescription isodose) doses decreases by 29 and 22%, respectively, as the number of static fields is increased from four to eight. Increasing the number of static fields to 12 only further reduces the high and intermediate dose volumes by 10 and 6%, respectively. The volume receiving the prescription dose is more than 3.5 times larger than the target volume for all treatment plans. Conclusions: Use of a multiple noncoplanar
Duality and modular invariance in rational conformal field theories
International Nuclear Information System (INIS)
Li Miao.
1990-03-01
We investigate the polynomial equations which should be satisfied by the duality data for a rational conformal field theory. We show that by these duality data we can construct some vector spaces which are isomorphic to the spaces of conformal blocks. One can construct explicitly the inner product for the former if one deals with a unitary theory. These vector spaces endowed with an inner product are the algebraic reminiscences of the Hilbert spaces in a Chern-Simons theory. As by-products, we show that the polynomial equations involving the modular transformations for the one-point blocks on the torus are not independent. And along the way, we discuss the reconstruction of the quantum group in a rational conformal theory. Finally, we discuss the solution of structure constants for a physical theory. Making some assumption, we obtain a neat solution. And this solution in turn implies that the quantum groups of the left sector and of the right sector must be the same, although the chiral algebras need not to be the same. Some examples are given. (orig.)
OPE convergence in non-relativistic conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Goldberger, Walter D.; Khandker, Zuhair University; Prabhu, Siddharth [Department of Physics, Yale University,New Haven, CT 06511 (United States); Physics Department, Boston University,Boston, MA 02215 (United States)
2015-12-09
Motivated by applications to the study of ultracold atomic gases near the unitarity limit, we investigate the structure of the operator product expansion (OPE) in non-relativistic conformal field theories (NRCFTs). The main tool used in our analysis is the representation theory of charged (i.e. non-zero particle number) operators in the NRCFT, in particular the mapping between operators and states in a non-relativistic “radial quantization” Hilbert space. Our results include: a determination of the OPE coefficients of descendant operators in terms of those of the underlying primary state, a demonstration of convergence of the (imaginary time) OPE in certain kinematic limits, and an estimate of the decay rate of the OPE tail inside matrix elements which, as in relativistic CFTs, depends exponentially on operator dimensions. To illustrate our results we consider several examples, including a strongly interacting field theory of bosons tuned to the unitarity limit, as well as a class of holographic models. Given the similarity with known statements about the OPE in SO(2,d) invariant field theories, our results suggest the existence of a bootstrap approach to constraining NRCFTs, with applications to bound state spectra and interactions. We briefly comment on a possible implementation of this non-relativistic conformal bootstrap program.
Yang-Baxter algebra - Integrable systems - Conformal quantum field theories
International Nuclear Information System (INIS)
Karowski, M.
1989-01-01
This series of lectures is based on investigations [1,2] of finite-size corrections for the six-vertex model by means of Bethe ansatz methods. In addition a review on applications of Yang-Baxter algebras and an introduction to the theory of integrable systems and the algebraic Bethe ansatz is presented. A Θ-vacuum like angle appearing in the RSOS-models is discussed. The continuum limit in the critical case of these statistical models is performed to obtain the minimal models of conformal quantum field theory. (author)
From the geometric quantization to conformal field theory
International Nuclear Information System (INIS)
Alekseev, A.; Shatashvili, S.
1990-01-01
Investigation of 2d conformal field theory in terms of geometric quantization is given. We quantize the so-called model space of the compact Lie group, Virasoro group and Kac-Moody group. In particular, we give a geometrical interpretation of the Virasoro discrete series and explain that this type of geometric quantization reproduces the chiral part of CFT (minimal models, 2d-gravity, WZNW theory). In the appendix we discuss the relation between classical (constant) r-matrices and this geometrical approach. (orig.)
Old and new topics in conformal field theory
International Nuclear Information System (INIS)
Zuber, J.B.
1991-01-01
These notes reflect the structure of the lectures given at the Kathmandu Summer School. They are made of two parts: the first is intended to be an elementary (and standard) introduction to conformal field theory, following the approach of Belavin, Polyakov and Zamolodchikov [1], together with a short and biaised review of some significant results. For the sake of brevity, the author shall not provide detailed references in that part. The second part presents some recent developments on some relations between c.f.t. and classical integrable systems (of KdV type), the so-called W-algebras and related results on the structure of singular vectors. (author)
The integrable structure of nonrational conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Bytsko, A. [Steklov Mathematics Institute, St. Petersburg (Russian Federation); Teschner, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2009-02-15
Using the example of Liouville theory, we show how the separation into left- and rightmoving degrees of freedom of a nonrational conformal field theory can be made explicit in terms of its integrable structure. The key observation is that there exist separate Baxter Q-operators for left- and right-moving degrees of freedom. Combining a study of the analytic properties of the Q-operators with Sklyanin's Separation of Variables Method leads to a complete characterization of the spectrum. Taking the continuum limit allows us in particular to rederive the Liouville reflection amplitude using only the integrable structure. (orig.)
Scalar field collapse in a conformally flat spacetime
Energy Technology Data Exchange (ETDEWEB)
Chakrabarti, Soumya; Banerjee, Narayan [Indian Institute of Science Education and Research, Kolkata, Department of Physical Sciences, Mohanpur, West Bengal (India)
2017-03-15
The collapse scenario of a scalar field along with a perfect fluid distribution was investigated for a conformally flat spacetime. The theorem for the integrability of an anharmonic oscillator has been utilized. For a pure power-law potential of the form φ{sup n+1}, it was found that a central singularity is formed which is covered by an apparent horizon for n > 0 and n < -3. Some numerical results have also been presented for a combination of two different powers of φ in the potential. (orig.)
Evaluating four-loop conformal Feynman integrals by D-dimensional differential equations
Energy Technology Data Exchange (ETDEWEB)
Eden, Burkhard [Institut für Mathematik und Physik, Humboldt-Universität zu Berlin,Zum großen Windkanal 6, 12489 Berlin (Germany); Smirnov, Vladimir A. [Skobeltsyn Institute of Nuclear Physics, Moscow State University,119992 Moscow (Russian Federation)
2016-10-21
We evaluate a four-loop conformal integral, i.e. an integral over four four-dimensional coordinates, by turning to its dimensionally regularized version and applying differential equations for the set of the corresponding 213 master integrals. To solve these linear differential equations we follow the strategy suggested by Henn and switch to a uniformly transcendental basis of master integrals. We find a solution to these equations up to weight eight in terms of multiple polylogarithms. Further, we present an analytical result for the given four-loop conformal integral considered in four-dimensional space-time in terms of single-valued harmonic polylogarithms. As a by-product, we obtain analytical results for all the other 212 master integrals within dimensional regularization, i.e. considered in D dimensions.
Evaluating four-loop conformal Feynman integrals by D-dimensional differential equations
Eden, Burkhard; Smirnov, Vladimir A.
2016-10-01
We evaluate a four-loop conformal integral, i.e. an integral over four four-dimensional coordinates, by turning to its dimensionally regularized version and applying differential equations for the set of the corresponding 213 master integrals. To solve these linear differential equations we follow the strategy suggested by Henn and switch to a uniformly transcendental basis of master integrals. We find a solution to these equations up to weight eight in terms of multiple polylogarithms. Further, we present an analytical result for the given four-loop conformal integral considered in four-dimensional space-time in terms of single-valued harmonic polylogarithms. As a by-product, we obtain analytical results for all the other 212 master integrals within dimensional regularization, i.e. considered in D dimensions.
On the group theoretical meaning of conformal field theories in the framework of coadjoint orbits
International Nuclear Information System (INIS)
Aratyn, H.; Nissimov, E.; Pacheva, S.
1990-01-01
We present a unifying approach to conformal field theories and other geometric models within the formalism of coadjoint orbits of infinite dimensional Lie groups with central extensions. Starting from the previously obtained general formula for the symplectic action in terms of two fundamental group one-cocycles, we derive the most general form of the Polyakov-Wiegmann composition laws for any geometric model. These composition laws are succinct expressions of all pertinent Noether symmetries. As a basic consequence we obtain Ward identities allowing for the exact quantum solvability of any geometric model. (orig.)
Universal spectrum of 2d conformal field theory in the large c limit
Thomas HartmanKavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030, U.S.A.; Christoph A. Keller(NHETC, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8019, U.S.A.); Bogdan Stoica(Walter Burke Institute for Theoretical Physics, California Institute of Technology, 452-48, Pasadena, CA 91125, U.S.A.)
2014-01-01
Two-dimensional conformal field theories exhibit a universal free energy in the high temperature limit $T \\to \\infty$, and a universal spectrum in the Cardy regime, $\\Delta \\to \\infty$. We show that a much stronger form of universality holds in theories with a large central charge $c$ and a sparse light spectrum. In these theories, the free energy is universal at all values of the temperature, and the microscopic spectrum matches the Cardy entropy for all $\\Delta \\geq c/6$. The same is true o...
Applications of three-dimensional image correlation in conformal radiotherapy
International Nuclear Information System (INIS)
Van Herk, M.; Gilhuijs, K.; Kwa, S.; Lebesque, J.; Muller, S.; De Munck, J.; Touw, A.; Kooy, H.
1995-01-01
The development of techniques for the registration of CT, MRI and SPECT creates new possibilities for improved target volume definition and quantitative image analysis. The discussed technique is based on chamfer matching and is suitable for automatic 3-D matching of CT with CT, CT with MRI, CT with SPECT and MRI with SPECT. By integrating CT with MRI, the diagnostic qualities of MRI are combined with the geometric accuracy of the planning CT. Significant differences in the delineation of the target volume for brain, head and neck and prostate tumors have been demonstrated when using integrated CT and MRI compared with using CT alone. In addition, integration of the planning CT with pre-operative scans improves knowledge of possible tumor extents. By first matching scans based on the bony anatomy and subsequently matching on an organ of study, relative motion of the organ is quantified accurately. In a study with 42 CT scans of 11 patients, magnitude and causes of prostate motion have been analysed. The most important motion of the prostate is a forward-backward rotation around a point near the apex caused by rectal volume difference. Significant correlations were also found between motion of the legs and the prostate. By integrating functional images made before and after radiotherapy with the planning CT, the relation between local change of lung function and delivered dose has been quantified accurately. The technique of chamfer matching is a convenient and more accurate alternative for the use of external markers in a CT/SPECT lung damage study. Also, damage visible in diagnostic scans can be related to radiation dose, thereby improving follow-up diagnostics. It can be concluded that 3-D image integration plays an important role in assessing and improving the accuracy of radiotherapy and is therefore indispensable for conformal therapy. However, user-friendly implementation of these techniques remains to be done to facilitate clinical application on a large
Applications of three-dimensional image correlation in conformal radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Van Herk, M; Gilhuijs, K; Kwa, S; Lebesque, J; Muller, S; De Munck, J; Touw, A [Nederlands Kanker Inst. ` Antoni van Leeuwenhoekhuis` , Amsterdam (Netherlands); Kooy, H [Harvard Medical School, Boston, MA (United States)
1995-12-01
The development of techniques for the registration of CT, MRI and SPECT creates new possibilities for improved target volume definition and quantitative image analysis. The discussed technique is based on chamfer matching and is suitable for automatic 3-D matching of CT with CT, CT with MRI, CT with SPECT and MRI with SPECT. By integrating CT with MRI, the diagnostic qualities of MRI are combined with the geometric accuracy of the planning CT. Significant differences in the delineation of the target volume for brain, head and neck and prostate tumors were demonstrated when using integrated CT and MRI compared with using CT alone. In addition, integration of the planning CT with pre-operative scans improves knowledge of possible tumor extents. By first matching scans based on the bony anatomy and subsequently matching on an organ of study, relative motion of the organ is quantified accurately. In a study with 42 CT scans of 11 patients, magnitude and causes of prostate motion were analysed. The most important motion of the prostate is a forward-backward rotation around a point near the apex caused by rectal volume difference. Significant correlations were also found between motion of the legs and the prostate. By integrating functional images made before and after radiotherapy with the planning CT, the relation between local change of lung function and delivered dose has been quantified accurately. The technique of chamfer matching is a convenient and more accurate alternative for the use of external markers in a CT/SPECT lung damage study. Also, damage visible in diagnostic scans can be related to radiation dose, thereby improving follow-up diagnostics. It can be concluded that 3-D image integration plays an important role in assessing and improving the accuracy of radiotherapy and is therefore indispensable for conformal therapy. However, user-friendly implementation of these techniques remains to be done to facilitate clinical application on a large scale.
Feasibility of four-dimensional conformal planning for robotic radiosurgery
International Nuclear Information System (INIS)
Schlaefer, A.; Fisseler, J.; Dieterich, S.; Shiomi, H.; Cleary, K.; Schweikard, A.
2005-01-01
Organ motion can have a severe impact on the dose delivered by radiation therapy, and different procedures have been developed to address its effects. Conventional techniques include breath hold methods and gating. A different approach is the compensation for target motion by moving the treatment beams synchronously. Practical results have been reported for robot based radiosurgery, where a linear accelerator mounted on a robotic arm delivers the dose. However, not all organs move in the same way, which results in a relative motion of the beams with respect to the body and the tissues in the proximity of the tumor. This relative motion can severely effect the dose delivered to critical structures. We propose a method to incorporate motion in the treatment planning for robotic radiosurgery to avoid potential overdosing of organs surrounding the target. The method takes into account the motion of all considered volumes, which is discretized for dose calculations. Similarly, the beam motion is taken into account and the aggregated dose coefficient over all discrete steps is used for planning. We simulated the treatment of a moving target with three different planning methods. First, we computed beam weights based on a 3D planning situation and simulated treatment with organ motion and the beams moving synchronously to the target. Second, beam weights were computed by the 4D planning method incorporating the organ and beam motion and treatment was simulated for beams moving synchronously to the target. Third, the beam weights were determined by the 4D planning method with the beams fixed during planning and simulation. For comparison we also give results for the 3D treatment plan if there was no organ motion and when the plan is delivered by fixed beams in the presence of organ motion. The results indicate that the new 4D method is preferable and can further improve the overall conformality of motion compensated robotic radiosurgery
Higher genus partition functions of meromorphic conformal field theories
International Nuclear Information System (INIS)
Gaberdiel, Matthias R.; Volpato, Roberto
2009-01-01
It is shown that the higher genus vacuum amplitudes of a meromorphic conformal field theory determine the affine symmetry of the theory uniquely, and we give arguments that suggest that also the representation content with respect to this affine symmetry is specified, up to automorphisms of the finite Lie algebra. We illustrate our findings with the self-dual theories at c = 16 and c = 24; in particular, we give an elementary argument that shows that the vacuum amplitudes of the E 8 x E 8 theory and the Spin(32)/Z 2 theory differ at genus g = 5. The fact that the discrepancy only arises at rather high genus is a consequence of the modular properties of higher genus amplitudes at small central charges. In fact, we show that for c ≤ 24 the genus one partition function specifies already the partition functions up to g ≤ 4 uniquely. Finally we explain how our results generalise to non-meromorphic conformal field theories.
Strings - Links between conformal field theory, gauge theory and gravity
International Nuclear Information System (INIS)
Troost, J.
2009-05-01
String theory is a candidate framework for unifying the gauge theories of interacting elementary particles with a quantum theory of gravity. The last years we have made considerable progress in understanding non-perturbative aspects of string theory, and in bringing string theory closer to experiment, via the search for the Standard Model within string theory, but also via phenomenological models inspired by the physics of strings. Despite these advances, many deep problems remain, amongst which a non-perturbative definition of string theory, a better understanding of holography, and the cosmological constant problem. My research has concentrated on various theoretical aspects of quantum theories of gravity, including holography, black holes physics and cosmology. In this Habilitation thesis I have laid bare many more links between conformal field theory, gauge theory and gravity. Most contributions were motivated by string theory, like the analysis of supersymmetry preserving states in compactified gauge theories and their relation to affine algebras, time-dependent aspects of the holographic map between quantum gravity in anti-de-Sitter space and conformal field theories in the bulk, the direct quantization of strings on black hole backgrounds, the embedding of the no-boundary proposal for a wave-function of the universe in string theory, a non-rational Verlinde formula and the construction of non-geometric solutions to supergravity
Dilogarithm identities in conformal field theory and group homology
International Nuclear Information System (INIS)
Dupont, J.L.
1994-01-01
Recently, Rogers' dilogarithm identities have attracted much attention in the setting of conformal field theory as well as lattice model calculations. One of the connecting threads is an identity of Richmond-Szekeres that appeared in the computation of central charges in conformal field theory. We show that the Richmond-Szekeres identity and its extension by Kirillov-Reshetikhin (equivalent to an identity found earlier by Lewin) can be interpreted as a lift of a generator of the third integral homology of a finite cyclic subgroup sitting inside the projective special linear group of all 2x2 real matrices viewed as a discrete group. This connection allows us to clarify a few of the assertions and conjectures stated in the work of Nahm-Recknagel-Terhoven concerning the role of algebraic K-theory and Thurston's program on hyperbolic 3-manifolds. Specifically, it is not related to hyperbolic 3-manifolds as suggested but is more appropriately related to the group manifold of the universal covering group of the projective special linear group of all 2x2 real matrices viewed as a topological group. This also resolves the weaker version of the conjecture as formulated by Kirillov. We end with a summary of a number of open conjectures on the mathematical side. (orig.)
Boundary conformal field theory analysis of the H+3 model
International Nuclear Information System (INIS)
Adorf, Hendrik
2008-01-01
The central topic of this thesis is the study of consistency conditions for the maximally symmetric branes of the H + 3 model. It is carried out by deriving constraints in the form of so-called shift equations and analysing their solutions. This results in explicit expressions for the one point functions in the various brane backgrounds. The brane spectrum becomes organized in certain continuous and discrete series. In the first part, we give an introduction to two dimensional conformal field theory (CFT) in the framework of vertex operator algebras and their modules. As this approach has been developed along with rational CFT, we pay attention to adapt it to the special needs of the nonrational H + 3 model. Part two deals with boundary CFT only. We start with a review of some basic techniques of boundary CFT and the Cardy-Lewellen sewing relations that will be at the heart of all following constructions. Afterwards, we introduce the systematics of brane solutions that we are going to follow. With the distinction between regular and irregular one point functions, we propose a new additional pattern according to which the brane solutions must be organized. We argue that all isospin dependencies must be subjected to the sewing constraints. At this point, the programme to be carried out is established and we are ready to derive the missing 1/2-shift equations for the various types of AdS 2 branes in order to make the list of this kind of equation complete. Then we address the b -2 /2-shift equations. It turns out that their derivation is not straightforward: One needs to extend the initial region of definition of a certain (boundary CFT) two point function to a suitable patch. Therefore, a continuation prescription has to be assumed. The most natural candidate is analytic continuation. We show that it can be carried out, although it is rather technical and involves the use of certain generalized hypergeometric functions in two variables. In this way, we derive a
The sewing technique for strings and conformal field theories
International Nuclear Information System (INIS)
Di Vecchia, P.
1989-01-01
We discuss recent results obtained from the sewing procedure for strings and conformal field theories. They are summarized by the N Point [String] g loop Vertex V N;g , that is the 'generating functional' of all correlation functions [scattering amplitudes] of the theory on a genus g Riemann surface. We discuss V N;g for free bosonic theory with arbitrary background charge and for fermionic and bosonic bc systems. By saturating those vertices with highest weight states we obtain in a simple way the correlation functions of the corresponding primary fields on genus g Riemann surfaces that reproduce known results including the correlation functions of a bosonic bc system, that present a number of peculiarities. We construct also V N;g for the bosonic and fermionic string. In particular this technique allows one to explicitly construct the measure of integration over the moduli and to study the various pinching limits in order to check the finiteness of superstring theories. (orig.)
International Nuclear Information System (INIS)
Hinterbichler, Kurt; Joyce, Austin; Khoury, Justin
2012-01-01
The pseudo-conformal scenario is an alternative to inflation in which the early universe is described by an approximate conformal field theory on flat, Minkowski space. Some fields acquire a time-dependent expectation value, which breaks the flat space so(4,2) conformal algebra to its so(4,1) de Sitter subalgebra. As a result, weight-0 fields acquire a scale invariant spectrum of perturbations. The scenario is very general, and its essential features are determined by the symmetry breaking pattern, irrespective of the details of the underlying microphysics. In this paper, we apply the well-known coset technique to derive the most general effective lagrangian describing the Goldstone field and matter fields, consistent with the assumed symmetries. The resulting action captures the low energy dynamics of any pseudo-conformal realization, including the U(1)-invariant quartic model and the Galilean Genesis scenario. We also derive this lagrangian using an alternative method of curvature invariants, consisting of writing down geometric scalars in terms of the conformal mode. Using this general effective action, we compute the two-point function for the Goldstone and a fiducial weight-0 field, as well as some sample three-point functions involving these fields
Twisted boundary states in c=1 coset conformal field theories
International Nuclear Information System (INIS)
Ishikawa, Hiroshi; Yamaguchi, Atsushi
2003-01-01
We study the mutual consistency of twisted boundary conditions in the coset conformal field theory G/H. We calculate the overlap of the twisted boundary states of G/H with the untwisted ones, and show that the twisted boundary states are consistently defined in the charge-conjugation modular invariant. The overlap of the twisted boundary states is expressed by the branching functions of a twisted affine Lie algebra. As a check of our argument, we study the diagonal coset theory so(2n) 1 +so(2n) 1 /so(2n) 2 , which is equivalent to the orbifold S 1 /Z 2 at a particular radius. We construct the boundary states twisted by the automorphisms of the unextended Dynkin diagram of so(2n), and show their mutual consistency by identifying their counterpart in the orbifold. For the triality of so(8), the twisted states of the coset theory correspond to neither the Neumann nor the Dirichlet boundary states of the orbifold and yield conformal boundary states that preserve only the Virasoro algebra. (author)
Connections on the state-space over conformal field theories
International Nuclear Information System (INIS)
Ranganathan, K.; Sonoda, H.; Zwiebach, B.
1994-01-01
Motivated by the problem of background independence of closed string field theory we study geometry on the infinite vector bundle of local fields over the space of conformal field theories (CFTs). With any connection we can associate an excluded domain D for the integral of marginal operators, and an operator one-form ω μ . The pair (D, ω μ ) determines the covariant derivative of any correlator of local fields. We obtain interesting classes of connections in which ω μ 's can be written in terms of CFT data. For these connections we compute their curvatures in terms of four-point correlators, D, and ω μ . Among these connections three are of particular interest. A flat, metric compatible connection Γ, and connections c and c with non-vanishing curvature, with the latter metric compatible. The flat connection cannot be used to do parallel transport over a finite distance. Parallel transport with either c or c, however, allows us to construct a CFT in the state-space of another CFT a finite distance away. The construction is given in the form of perturbation theory manifestly free of divergences. (orig.)
Conformal techniques in string theory and string field theory
International Nuclear Information System (INIS)
Giddings, S.B.
1987-01-01
The application of some conformal and Riemann surface techniques to string theory and string field theory is described. First a brief review of Riemann surface techniques and of the Polyakov approach to string theory is presented. This is followed by a discussion of some features of string field theory and of its Feynman rules. Specifically, it is shown that the Feynman diagrams for Witten's string field theory respect modular invariance, and in particular give a triangulation of moduli space. The Polyakov formalism is then used to derive the Feynman rules that should follow from this theory upon gauge-fixing. It should also be possible to apply this derivation to deduce the Feynman rules for other gauge-fixed string field theories. Following this, Riemann surface techniques are turned to the problem of proving the equivalence of the Polyakov and light-cone formalisms. It is first shown that the light-cone diagrams triangulate moduli space. Then the Polyakov measure is worked out for these diagrams, and shown to equal that deduced from the light-cone gauge fixed formalism. Also presented is a short description of the comparison of physical states in the two formalisms. The equivalence of the two formalisms in particular constitutes a proof of the unitarity of the Polyakov framework for the closed bosonic string
Free ◻{sup k} scalar conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Brust, Christopher [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario N2L 2Y5 (Canada); Hinterbichler, Kurt [CERCA, Department of Physics, Case Western Reserve University,10900 Euclid Ave, Cleveland, OH 44106 (United States)
2017-02-13
We consider the generalizations of the free U(N) and O(N) scalar conformal field theories to actions with higher powers of the Laplacian ◻{sup k}, in general dimension d. We study the spectra, Verma modules, anomalies and OPE of these theories. We argue that in certain d and k, the spectrum contains zero norm operators which are both primary and descendant, as well as extension operators which are neither primary nor descendant. In addition, we argue that in even dimensions d≤2k, there are well-defined operator algebras which are related to the ◻{sup k} theories and are novel in that they have a finite number of single-trace states.
Conformal Field Theory, Automorphic Forms and Related Topics
Weissauer, Rainer; CFT 2011
2014-01-01
This book, part of the series Contributions in Mathematical and Computational Sciences, reviews recent developments in the theory of vertex operator algebras (VOAs) and their applications to mathematics and physics. The mathematical theory of VOAs originated from the famous monstrous moonshine conjectures of J.H. Conway and S.P. Norton, which predicted a deep relationship between the characters of the largest simple finite sporadic group, the Monster, and the theory of modular forms inspired by the observations of J. MacKay and J. Thompson. The contributions are based on lectures delivered at the 2011 conference on Conformal Field Theory, Automorphic Forms and Related Topics, organized by the editors as part of a special program offered at Heidelberg University that summer under the sponsorship of the MAThematics Center Heidelberg (MATCH).
Path operator algebras in conformal quantum field theories
International Nuclear Information System (INIS)
Roesgen, M.
2000-10-01
Two different kinds of path algebras and methods from noncommutative geometry are applied to conformal field theory: Fusion rings and modular invariants of extended chiral algebras are analyzed in terms of essential paths which are a path description of intertwiners. As an example, the ADE classification of modular invariants for minimal models is reproduced. The analysis of two-step extensions is included. Path algebras based on a path space interpretation of character identities can be applied to the analysis of fusion rings as well. In particular, factorization properties of character identities and therefore of the corresponding path spaces are - by means of K-theory - related to the factorization of the fusion ring of Virasoro- and W-algebras. Examples from nonsupersymmetric as well as N=2 supersymmetric minimal models are discussed. (orig.)
Conformal field theory and functions of hypergeometric type
International Nuclear Information System (INIS)
Isachenkov, Mikhail
2016-03-01
Conformal field theory provides a universal description of various phenomena in natural sciences. Its development, swift and successful, belongs to the major highlights of theoretical physics of the late XX century. In contrast, advances of the theory of hypergeometric functions always assumed a slower pace throughout the centuries of its existence. Functional identities studied by this mathematical discipline are fascinating both in their complexity and beauty. This thesis investigates the interrelation of two subjects through a direct analysis of three CFT problems: two-point functions of the 2d strange metal CFT, three-point functions of primaries of the non-rational Toda CFT and kinematical parts of Mellin amplitudes for scalar four-point functions in general dimensions. We flash out various generalizations of hypergeometric functions as a natural mathematical language for two of these problems. Several new methods inspired by extensions of classical results on hypergeometric functions, are presented.
Circular Wilson loops in defect conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Aguilera-Damia, Jeremías; Correa, Diego H. [Instituto de Física La Plata, CONICET, Universidad Nacional de La Plata,C.C. 67, 1900 La Plata (Argentina); Giraldo-Rivera, Victor I. [International Centre for Theoretical Sciences (ICTS-TIFR),Shivakote, Hesaraghatta Hobli, Bengaluru 560089 (India)
2017-03-06
We study a D3-D5 system dual to a conformal field theory with a codimension-one defect that separates regions where the ranks of the gauge groups differ by k. With the help of this additional parameter, as observed by Nagasaki, Tanida and Yamaguchi, one can define a double scaling limit in which the quantum corrections are organized in powers of λ/k{sup 2}, which should allow to extrapolate results between weak and strong coupling regimes. In particular we consider a radius R circular Wilson loop placed at a distance L, whose internal space orientation is given by an angle χ. We compute its vacuum expectation value and show that, in the double scaling limit and for small χ and small L/R, weak coupling results can be extrapolated to the strong coupling limit.
Conformal field theory and functions of hypergeometric type
Energy Technology Data Exchange (ETDEWEB)
Isachenkov, Mikhail
2016-03-15
Conformal field theory provides a universal description of various phenomena in natural sciences. Its development, swift and successful, belongs to the major highlights of theoretical physics of the late XX century. In contrast, advances of the theory of hypergeometric functions always assumed a slower pace throughout the centuries of its existence. Functional identities studied by this mathematical discipline are fascinating both in their complexity and beauty. This thesis investigates the interrelation of two subjects through a direct analysis of three CFT problems: two-point functions of the 2d strange metal CFT, three-point functions of primaries of the non-rational Toda CFT and kinematical parts of Mellin amplitudes for scalar four-point functions in general dimensions. We flash out various generalizations of hypergeometric functions as a natural mathematical language for two of these problems. Several new methods inspired by extensions of classical results on hypergeometric functions, are presented.
Effective field theory dimensional regularization
International Nuclear Information System (INIS)
Lehmann, Dirk; Prezeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed
Effective field theory dimensional regularization
Lehmann, Dirk; Prézeau, Gary
2002-01-01
A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinematic variables. Simple diagrammatic rules are derived for the regularization of arbitrary one-loop graphs and the generalization to higher loops is discussed.
Pressure and Compressibility of Conformal Field Theories from the AdS/CFT Correspondence
Directory of Open Access Journals (Sweden)
Brian P. Dolan
2016-05-01
Full Text Available The equation of state associated with N = 4 supersymmetric Yang–Mills in four dimensions, for S U ( N in the large N limit, is investigated using the AdS/CFT correspondence. An asymptotically AdS black-hole on the gravity side provides a thermal background for the Yang–Mills theory on the boundary in which the cosmological constant is equivalent to a volume. The thermodynamic variable conjugate to the cosmological constant is a pressure, and the P - V diagram of the quark-gluon plasma is studied. It is known that there is a critical point where the heat capacity diverges, and this is reflected in the isothermal compressibility. Critical exponents are derived and found to be mean field in the large N limit. The same analysis applied to three- and six-dimensional conformal field theories again yields mean field exponents associated with the compressibility at the critical point.
A quantum group structure in integrable conformal field theories
International Nuclear Information System (INIS)
Smit, D.J.
1990-01-01
We discuss a quantization prescription of the conformal algebras of a class of d=2 conformal field theories which are integrable. We first give a geometrical construction of certain extensions of the classical Virasoro algebra, known as classical W algebras, in which these algebras arise as the Lie algebra of the second Hamiltonian structure of a generalized Korteweg-de Vries hierarchy. This fact implies that the W algebras, obtained as a reduction with respect to the nilpotent subalgebras of the Kac-Moody algebra, describe the intergrability of a Toda field theory. Subsequently we determine the coadjoint operators of the W algebras, and relate these to classical Yang-Baxter matrices. The quantization of these algebras can be carried out using the concept of a so-called quantum group. We derive the condition under which the representations of these quantum groups admit a Hilbert space completion by exploring the relation with the braid group. Then we consider a modification of the Miura transformation which we use to define a quantum W algebra. This leads to an alternative interpretation of the coset construction for Kac-Moody algebras in terms of nonlinear integrable hierarchies. Subsequently we use the connection between the induced braid group representations and the representations of the mapping class group of Riemann surfaces to identify an action of the W algebras on the moduli space of stable curves, and we give the invariants of this action. This provides a generalization of the situation for the Virasoro algebra, where such an invariant is given by the so-called Mumford form which describes the partition function of the bosonic string. (orig.)
McNutt, David D.
2017-11-01
We introduce three approaches to generate curvature invariants that transform covariantly under a conformal transformation of a four-dimensional spacetime. For any black hole conformally related to a stationary black hole, we show how a set of conformally covariant invariants can be combined to produce a conformally covariant invariant that detects the event horizon of the conformally related black hole. As an application we consider the rotating dynamical black holes conformally related to the Kerr-Newman-Unti-Tamburino-(anti)-de Sitter spacetimes and construct an invariant that detects the conformal Killing horizon along with a second invariant that detects the conformal stationary limit surface. In addition, we present necessary conditions for a dynamical black hole to be conformally related to a stationary black hole and apply these conditions to the ingoing Kerr-Vaidya and Vaidya black hole solutions to determine if they are conformally related to stationary black holes for particular choices of the mass function. While two of the three approaches cannot be generalized to higher dimensions, we discuss the existence of a conformally covariant invariant that will detect the event horizon for any higher dimensional black hole conformally related to a stationary black hole which admits at least two conformally covariant invariants, including all vacuum spacetimes.
Extended U(1) conformal field theories and Zk-parafermions
International Nuclear Information System (INIS)
Furlan, P.; Paunov, R.R.; Todorov, I.T.
1992-01-01
A constructive approach is developed for studying local chiral algebras generated by a pair of oppositely charged fields ψ(z, ±g) such that the operator product expansion (OPE) of ψ(z 1 ,g) ψ(z 2 , -g) involves a U (1) current. The main tool in the study is the factorization property of the charged fields (exhibited in [PT 2.3]) for Virasoro central charge c k -parafermions. The case Δ 2 =4(Δ 1 -1), where Δ sν =Δ K-ν (Δ 0 =0) ore conformal dimensions of the parafemionic currents, is studied in detail. For Δ Τ = 2Τ(1 - Δ/k) the theory is related to GEPNER'S [GE] Z 2 [SO (k)] parafermions and the corresponding quantum field theroretic (QFT) representations of the chiral algebra are displayed. The Coulomb gas method of [CR] is further developed to include an explicit construction of the basic parafermionic current φ of wight Δ = Δ 1 . The characters of the positive energy representations of the local chiral algebra are written as sums of products of Kac,s string functions and classical Θ-functions. (orig.)
Complete conformal field theory solution of a chiral six-point correlation function
International Nuclear Information System (INIS)
Simmons, Jacob J H; Kleban, Peter
2011-01-01
Using conformal field theory, we perform a complete analysis of the chiral six-point correlation function C(z)= 1,2 φ 1,2 Φ 1/2,0 (z, z-bar )φ 1,2 φ 1,2 >, with the four φ 1,2 operators at the corners of an arbitrary rectangle, and the point z = x + iy in the interior. We calculate this for arbitrary central charge (equivalently, SLE parameter κ > 0). C is of physical interest because for percolation (κ = 6) and many other two-dimensional critical points, it specifies the density at z of critical clusters conditioned to touch either or both vertical ends of the rectangle, with these ends 'wired', i.e. constrained to be in a single cluster, and the horizontal ends free. The correlation function may be written as the product of an algebraic prefactor f and a conformal block G, where f = f(x, y, m), with m a cross-ratio specified by the corners (m determines the aspect ratio of the rectangle). By appropriate choice of f and using coordinates that respect the symmetry of the problem, the conformal block G is found to be independent of either y or x, and given by an Appell function.
Full three-dimensional isotropic carpet cloak designed by quasi-conformal transformation optics.
Silva, Daniely G; Teixeira, Poliane A; Gabrielli, Lucas H; Junqueira, Mateus A F C; Spadoti, Danilo H
2017-09-18
A fully three-dimensional carpet cloak presenting invisibility in all viewing angles is theoretically demonstrated. The design is developed using transformation optics and three-dimensional quasi-conformal mapping. Parametrization strategy and numerical optimization of the coordinate transformation deploying a quasi-Newton method is applied. A discussion about the minimum achievable anisotropy in the 3D transformation optics is presented. The method allows to reduce the anisotropy in the cloak and an isotropic medium could be considered. Numerical simulations confirm the strategy employed enabling the design of an isotropic reflectionless broadband carpet cloak independently of the incident light direction and polarization.
An introduction to conformal field theory in two dimensions and string theory
International Nuclear Information System (INIS)
Wadia, S.R.
1989-01-01
This paper provides information on The S-Matrix; Elements of conformally invariant field theory in 2-dim.; The Virasoro gauge conditions; Some representations of the Virasoro algebra; The S-matrix of the Bosonic string theory; Super conformal field theory; Superstring; superstring spectrum and GSO projection; The (β,γ) ghost system; BRST formulation; and String propagation in background fields
Shape Dependence of Holographic Rényi Entropy in Conformal Field Theories
Dong, Xi
2016-06-01
We develop a framework for studying the well-known universal term in the Rényi entropy for an arbitrary entangling region in four-dimensional conformal field theories that are holographically dual to gravitational theories. The shape dependence of the Rényi entropy Sn is described by two coefficients: fb(n ) for traceless extrinsic curvature deformations and fc(n ) for Weyl tensor deformations. We provide the first calculation of the coefficient fb(n ) in interacting theories by relating it to the stress tensor one-point function in a deformed hyperboloid background. The latter is then determined by a straightforward holographic calculation. Our results show that a previous conjecture fb(n )=fc(n ), motivated by surprising evidence from a variety of free field theories and studies of conical defects, fails holographically.
Conformal generally covariant quantum field theory. The scalar field and its Wick products
Energy Technology Data Exchange (ETDEWEB)
Pinamonti, N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2008-06-15
In this paper we generalize the construction of generally covariant quantum theories given in [R. Brunetti, K. Fredenhagen, R. Verch, Commun. Math. Phys. 237, 31 (2003)] to encompass the conformal covariant case. After introducing the abstract framework, we discuss the massless conformally coupled Klein Gordon field theory, showing that its quantization corresponds to a functor between two certain categories. At the abstract level, the ordinary fields, could be thought as natural transformations in the sense of category theory. We show that, the Wick monomials without derivatives (Wick powers), can be interpreted as fields in this generalized sense, provided a non trivial choice of the renormalization constants is given. A careful analysis shows that the transformation law of Wick powers is characterized by a weight, and it turns out that the sum of fields with different weights breaks the conformal covariance. At this point there is a difference between the previously given picture due to the presence of a bigger group of covariance. It is furthermore shown that the construction does not depend upon the scale {mu} appearing in the Hadamard parametrix, used to regularize the fields. Finally, we briefly discuss some further examples of more involved fields. (orig.)
Conformal generally covariant quantum field theory. The scalar field and its Wick products
International Nuclear Information System (INIS)
Pinamonti, N.
2008-06-01
In this paper we generalize the construction of generally covariant quantum theories given in [R. Brunetti, K. Fredenhagen, R. Verch, Commun. Math. Phys. 237, 31 (2003)] to encompass the conformal covariant case. After introducing the abstract framework, we discuss the massless conformally coupled Klein Gordon field theory, showing that its quantization corresponds to a functor between two certain categories. At the abstract level, the ordinary fields, could be thought as natural transformations in the sense of category theory. We show that, the Wick monomials without derivatives (Wick powers), can be interpreted as fields in this generalized sense, provided a non trivial choice of the renormalization constants is given. A careful analysis shows that the transformation law of Wick powers is characterized by a weight, and it turns out that the sum of fields with different weights breaks the conformal covariance. At this point there is a difference between the previously given picture due to the presence of a bigger group of covariance. It is furthermore shown that the construction does not depend upon the scale μ appearing in the Hadamard parametrix, used to regularize the fields. Finally, we briefly discuss some further examples of more involved fields. (orig.)
International Nuclear Information System (INIS)
Widom, Julia R; Marcus, Andrew H; Johnson, Neil P; Von Hippel, Peter H
2013-01-01
We have observed the conformation-dependent electronic coupling between the monomeric subunits of a dinucleotide of 2-aminopurine (2-AP), a fluorescent analogue of the nucleic acid base adenine. This was accomplished by extending two-dimensional fluorescence spectroscopy (2D FS)—a fluorescence-detected variation of 2D electronic spectroscopy—to excite molecular transitions in the ultraviolet (UV) regime. A collinear sequence of four ultrafast laser pulses centered at 323 nm was used to resonantly excite the coupled transitions of 2-AP dinucleotide. The phases of the optical pulses were continuously swept at kilohertz frequencies, and the ensuing nonlinear fluorescence was phase-synchronously detected at 370 nm. Upon optimization of a point–dipole coupling model to our data, we found that in aqueous buffer the 2-AP dinucleotide adopts an average conformation in which the purine bases are non-helically stacked (center-to-center distance R 12 = 3.5 ± 0.5 Å , twist angle θ 12 = 5° ± 5° ), which differs from the conformation of such adjacent bases in duplex DNA. These experiments establish UV–2D FS as a method for examining the local conformations of an adjacent pair of fluorescent nucleotides substituted into specific DNA or RNA constructs, which will serve as a powerful probe to interpret, in structural terms, biologically significant local conformational changes within the nucleic acid framework of protein–nucleic acid complexes. (paper)
Energy Technology Data Exchange (ETDEWEB)
Crosta, Dante; Elitseche, Luis [Repsol YPF (Argentina); Gutierrez, Mauricio; Ansah, Joe; Everett, Don [Halliburton Argentina S.A., Buenos Aires (Argentina)
2004-07-01
Minimizing the amount of unwanted water production is an important goal at the Barrancas field. This paper describes a selection process for candidate injection wells that is part of a pilot conformance project aimed at improving vertical injection profiles, reducing water cut in producing wells, and improving ultimate oil recovery from this field. The well selection process is based on a review of limited reservoir information available for this field to determine inter-well communications. The methodology focuses on the best use of available information, such as production and injection history, well intervention files, open hole logs and injectivity surveys. After the candidate wells were selected and potential water injection channels were identified, conformance treatment design and future performance of wells in the selected pilot area were evaluated using a new 3 -D conformance simulator, developed specifically for optimization of the design and placement of unwanted fluid shut-off treatments. Thus, when acceptable history match ing of the pilot area production was obtained, the 3 -D simulator was used to: evaluate the required volume of selected conformance treatment fluid; review expected pressures and rates during placement;. model temperature behavior; evaluate placement techniques, and forecast water cut reduction and incremental oil recovery from the producers in this simulated section of the pilot area. This paper outlines a methodology for selecting candidate wells for conformance treatments. The method involves application of several engineering tools, an integral component of which is a user-friendly conformance simulator. The use of the simulator has minimized data preparation time and allows the running of sensitivity cases quickly to explore different possible scenarios that best represent the reservoir. The proposed methodology provides an efficient means of identifying conformance problems and designing optimized solutions for these individual
Conformal techniques for OPE in asymptotically free quantum field theory
International Nuclear Information System (INIS)
Craigie, N.S.; Dobrev, V.K.
1982-06-01
We discuss the relationship between the short-distance behaviour of vertex functions and conformal invariance in asymptotically free theories. We show how conformal group techniques can be used to derive spectral representations of wave functions and vertex functions in QCD. (author)
Popularity, likeability, and peer conformity: Four field experiments
Gommans, R.; Sandstrom, M.J.; Stevens, G.W.J.M.; Bogt, T.F.M. ter; Cillessen, A.H.N.
2017-01-01
Adolescents tend to alter their attitudes and behaviors to match those of others; a peer influence process named peer conformity. This study investigated to what extent peer conformity depended on the status (popularity and likeability) of the influencer and the influencee. The study consisted of
Global operator expansions in conformally invariant relativistic quantum field theory
International Nuclear Information System (INIS)
Schoer, B.; Swieca, J.A.; Voelkel, A.H.
1974-01-01
A global conformal operator expansions in the Minkowski region in several models and their formulation in the general theory is presented. Whereas the vacuum expansions are termwise manisfestly conformal invariant, the expansions away from the vacuum do not share this property
Low dimensional field theories and condensed matter physics
International Nuclear Information System (INIS)
Nagaoka, Yosuke
1992-01-01
This issue is devoted to the Proceedings of the Fourth Yukawa International Seminar (YKIS '91) on Low Dimensional Field Theories and Condensed Matter Physics, which was held on July 28 to August 3 in Kyoto. In recent years there have been great experimental discoveries in the field of condensed matter physics: the quantum Hall effect and the high temperature superconductivity. Theoretical effort to clarify mechanisms of these phenomena revealed that they are deeply related to the basic problem of many-body systems with strong correlation. On the other hand, there have been important developments in field theory in low dimensions: the conformal field theory, the Chern-Simons gauge theory, etc. It was found that these theories work as a powerful method of approach to the problems in condensed matter physics. YKIS '91 was devoted to the study of common problems in low dimensional field theories and condensed matter physics. The 17 of the presented papers are collected in this issue. (J.P.N.)
Indices for 6 dimensional superconformal field theories
International Nuclear Information System (INIS)
Kim, Seok; Lee, Kimyeong
2017-01-01
We review some recent developments in the 6 dimensional (2, 0) superconformal field theories, focusing on their Bogomol’nyi–Prasad–Sommerfield (BPS) spectra in the Coulomb and symmetric phases computed by various Witten indices. We shall discuss the instanton partition function of 5d maximal super-Yang–Mills theory, and the 6d superconformal index. (topical review)
Loops in AdS from conformal field theory
Aharony, Ofer; Alday, Luis F.; Bissi, Agnese; Perlmutter, Eric
2017-07-01
We propose and demonstrate a new use for conformal field theory (CFT) crossing equations in the context of AdS/CFT: the computation of loop amplitudes in AdS, dual to non-planar correlators in holographic CFTs. Loops in AdS are largely unexplored, mostly due to technical difficulties in direct calculations. We revisit this problem, and the dual 1 /N expansion of CFTs, in two independent ways. The first is to show how to explicitly solve the crossing equations to the first subleading order in 1 /N 2, given a leading order solution. This is done as a systematic expansion in inverse powers of the spin, to all orders. These expansions can be resummed, leading to the CFT data for finite values of the spin. Our second approach involves Mellin space. We show how the polar part of the four-point, loop-level Mellin amplitudes can be fully reconstructed from the leading-order data. The anomalous dimensions computed with both methods agree. In the case of ϕ 4 theory in AdS, our crossing solution reproduces a previous computation of the one-loop bubble diagram. We can go further, deriving the four-point scalar triangle diagram in AdS, which had never been computed. In the process, we show how to analytically derive anomalous dimensions from Mellin amplitudes with an infinite series of poles, and discuss applications to more complicated cases such as the N = 4 super-Yang-Mills theory.
Noncommutative conformally coupled scalar field cosmology and its commutative counterpart
International Nuclear Information System (INIS)
Barbosa, G.D.
2005-01-01
We study the implications of a noncommutative geometry of the minisuperspace variables for the Friedmann-Robertson-Walker universe with a conformally coupled scalar field. The investigation is carried out by means of a comparative study of the universe evolution in four different scenarios: classical commutative, classical noncommutative, quantum commutative, and quantum noncommutative, the last two employing the Bohmian formalism of quantum trajectories. The role of noncommutativity is discussed by drawing a parallel between its realizations in two possible frameworks for physical interpretation: the NC frame, where it is manifest in the universe degrees of freedom, and in the C frame, where it is manifest through θ-dependent terms in the Hamiltonian. As a result of our comparative analysis, we find that noncommutative geometry can remove singularities in the classical context for sufficiently large values of θ. Moreover, under special conditions, the classical noncommutative model can admit bouncing solutions characteristic of the commutative quantum Friedmann-Robertson-Walker universe. In the quantum context, we find nonsingular universe solutions containing bounces or being periodic in the quantum commutative model. When noncommutativity effects are turned on in the quantum scenario, they can introduce significant modifications that change the singular behavior of the universe solutions or that render them dynamical whenever they are static in the commutative case. The effects of noncommutativity are completely specified only when one of the frames for its realization is adopted as the physical one. Nonsingular solutions in the NC frame can be mapped into singular ones in the C frame
Energy Technology Data Exchange (ETDEWEB)
Castro, A.L.S.; Campos, T.P.R., E-mail: radioterapia.andre@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear
2016-11-01
Radiotherapy is the most used clinical method used for brain metastases treatment, the most frequent secondary tumors provided by breast, lung and melanomas as primary origin. The protocols often use high daily doses and, depending on the irradiation technique there is high probability of complications in health tissues. In order to minimize adverse effects, it is important the dosimetric analysis of three-dimensional radiotherapy planning through tomographic images or, concerning to the 2D simulations, by the application of techniques that optimize dose distribution by increasing the homogeneity. The study aimed to compare the 2D and 3D conformal planning for total brain irradiation in a individual equivalent situation and evaluate the progress of these planning applying the field in field technique. The methodology consisted of simulating a two-dimensional planning, reproduce it on a set of tomographic images and compare it with the conformal plan for two fields and four fields (field in field). The results showed no significant difference between 2D and 3D planning for whole brain irradiation, and the field in field technique significantly improved the dose distribution in brain volume compared with two fields for the proposal situation. As conclusion, the two-dimensional plane for the four fields described was viable for whole brain irradiation in the treatment of brain metastases at the proposal situation. (author)
On the conformal transformation in *gλμ-unified field theory
International Nuclear Information System (INIS)
Lee, Il Young
1986-01-01
Chung gave the complete set of the general solutions of Einstein's equations in the Einstein's * g λμ -unified field theory for all classes and all possible indices of interia. In the present paper we shall investigate how the conformal transformation enforces the connection and give the complete relations between connections in * g λμ -unified field theory. Also we shall investigate how S λ is transformed by the conformal transformation and give conformally invariant connection. (Author)
Logarithmic conformal field theories as limits of ordinary CFTs and some physical applications
International Nuclear Information System (INIS)
Cardy, John
2013-01-01
We describe an approach to logarithmic conformal field theories as limits of sequences of ordinary conformal field theories with varying central charge c. Logarithmic behaviour arises from degeneracies in the spectrum of scaling dimensions at certain values of c. The theories we consider are all invariant under some internal symmetry group, and logarithmic behaviour occurs when the decomposition of the physical observables into irreducible operators becomes singular. Examples considered are quenched random magnets using the replica formalism, self-avoiding walks as the n → 0 limit of the O(n) model, and percolation as the limit Q → 1 of the Potts model. In these cases we identify logarithmic operators and pay particular attention to how the c → 0 paradox is resolved and how the b-parameter is evaluated. We also show how this approach gives information on logarithmic behaviour in the extended Ising model, uniform spanning trees and the O( − 2) model. Most of our results apply to general dimensionality. We also consider massive logarithmic theories and, in two dimensions, derive sum rules for the effective central charge and the b-parameter. (review)
Note on non-vacuum conformal family contributions to Rényi entropy in two-dimensional CFT
Zhang, Jia-ju
2017-06-01
We calculate the contributions of a general non-vacuum conformal family to Rényi entropy in two-dimensional conformal field theory (CFT). The primary operator of the conformal family can be either non-chiral or chiral, and we denote its scaling dimension by Δ. For the case of two short intervals on a complex plane, we expand the Rényi mutual information by the cross ratio x to order x 2Δ+2. For the case of one interval on a torus with low temperature, we expand the Rényi entropy by q=exp(-2πβ/L), with β being the inverse temperature and L being the spatial period, to order q Δ+2. To make the result meaningful, we require that the scaling dimension Δ cannot be too small. For two intervals on a complex plane we need Δ > 1, and for one interval on a torus we need Δ > 2. We work in the small Newton constant limit on the gravity side and so a large central charge limit on the CFT side, and find matches of gravity and CFT results. Supported by ERC Starting Grant 637844-HBQFTNCER
International Nuclear Information System (INIS)
Park, Young Je; Ahn, Yong Chan; Park, Won; Ju, Sang Gyu; Nam, Hee Rim; Oh, Dong Ryul; Park, Hee Chul
2006-01-01
This study is to evaluate the xerostomia following 3-dimensional conformal radiation therapy (3D CRT) in nasopharynx cancer patients using the xerostomia questionnaire score (XQS). Questionnaire study was done on 51 patients with nasopharynx cancer who received 3D CRT from Dec. 2000 to Aug. 2005. 3D CRT technique is based on 'serial shrinking field' concept by 3 times of computed tomography (CT) simulation. Total target dose to the primary tumor was 72 Gy with 1.8 Gy daily fractions. Xerostomia was assessed with 4-questions XQS, and the associations between XQS and time elapsed after RT, age, sex, stage, concurrent chemotherapy, an parotid dose were analyzed. Concurrent chemotherapy was given to 40 patients and RT alone was given to 11 patients. The median time elapsed after 3D CRT was 20 (1 ∼ 58) months and the mean XQS of all 51 patients was 8.4 ± 1.9 (6 ∼ 14). XQS continuously and significantly decreased over time after 3D CRT (χ 2 -0.484, ρ < 0.05). There was no significant difference in XQS according to sex, age, and stag. However, XQS of concurrent chemotherapy patients was significantly higher than RT alone patients (ρ = 0.001). XQS of patients receiving total mean parotid dose ≥ 35 Gy was significantly higher than < 35 Gy (ρ = 0.05). Decreasing tendency of XQS over time after 3D CRT was observed. Concurrent chemotherapy and total mean parotid dose ≥ 35 Gy were suggested to adversely affect radiation-induced xerostomia
Infinite-component conformal fields. Spectral representation of the two-point function
International Nuclear Information System (INIS)
Zaikov, R.P.; Tcholakov, V.
1975-01-01
The infinite-component conformal fields (with respect to the stability subgroup) are considered. The spectral representation of the conformally invariant two-point function is obtained. This function is nonvanishing as/lso for one ''fundamental'' and one infinite-component field
Computing black hole entropy in loop quantum gravity from a conformal field theory perspective
International Nuclear Information System (INIS)
Agulló, Iván; Borja, Enrique F.; Díaz-Polo, Jacobo
2009-01-01
Motivated by the analogy proposed by Witten between Chern-Simons and conformal field theories, we explore an alternative way of computing the entropy of a black hole starting from the isolated horizon framework in loop quantum gravity. The consistency of the result opens a window for the interplay between conformal field theory and the description of black holes in loop quantum gravity
One-dimensional phased array with mechanical motion for conformal ultrasound hyperthermia
International Nuclear Information System (INIS)
Ju, Kuen-Cheng; Chen, Yung-Yaw; Lin, Win-Li; Kuo, Te-Son
2003-01-01
This paper investigates the feasibility of conformal heating for external ultrasound hyperthermia by using a phased array transducer with mechanical motion. In this system, a one-dimensional phased array is arranged on a shaft and moves along the shaft, while dynamically focusing on the planning target volume (PTV) with numerous focal spots. To prevent overheating in the intervening tissue between the skin and the PTV, the shaft and the phased array are rotated together to enlarge the acoustical window. With the purpose of conformal heating, the power deposition of the PTV is constructed by combinations of the focal spots and an iterative gradient descent method is then used to determine an optimal set of power weightings for the focal spots. Different tumour shapes are evaluated and the simulation results demonstrate that the volume percentage of the PTV with temperatures higher than 43 deg. C is over 95%. The overheating volume outside the PTV is less than 25% of the PTV. This method provides good conformal heating for external ultrasound hyperthermia. The concept of combining electrical focusing and mechanical motion has the advantages of both enlarging the acoustic window and providing dynamic focusing ability, which is essential for successful conformal heating
International Nuclear Information System (INIS)
Moore, G.; Seiberg, N.
1989-01-01
All known rational conformal field theories may be obtained from (2+1)-dimensional Chern-Simons gauge theories by appropriate choice of gauge group. We conjecture that all rational field theories are classified by groups via (2+1)-dimensional Chern-Simons gauge theories. (orig.)
Light-cone AdS/CFT-adapted approach to AdS fields/currents, shadows, and conformal fields
Energy Technology Data Exchange (ETDEWEB)
Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991 (Russian Federation)
2015-10-16
Light-cone gauge formulation of fields in AdS space and conformal field theory in flat space adapted for the study of AdS/CFT correspondence is developed. Arbitrary spin mixed-symmetry fields in AdS space and arbitrary spin mixed-symmetry currents, shadows, and conformal fields in flat space are considered on an equal footing. For the massless and massive fields in AdS and the conformal fields in flat space, simple light-cone gauge actions leading to decoupled equations of motion are found. For the currents and shadows, simple expressions for all 2-point functions are also found. We demonstrate that representation of conformal algebra generators on space of currents, shadows, and conformal fields can be built in terms of spin operators entering the light-cone gauge formulation of AdS fields. This considerably simplifies the study of AdS/CFT correspondence. Light-cone gauge actions for totally symmetric arbitrary spin long conformal fields in flat space are presented. We apply our approach to the study of totally antisymmetric (one-column) and mixed-symmetry (two-column) fields in AdS space and currents, shadows, and conformal fields in flat space.
International Nuclear Information System (INIS)
Kortmann, Rolf D.; Becker, Gerd; Perelmouter, Jury; Buchgeister, Markus; Meisner, Christoph; Bamberg, Michael
1999-01-01
Purpose: To assess the accuracy of field alignment in patients undergoing three-dimensional (3D) conformal radiotherapy of brain tumors, and to evaluate the impact on the definition of planning target volume and control procedures. Methods and Materials: Geometric accuracy was analyzed in 20 patients undergoing fractionated stereotactic conformal radiotherapy for brain tumors. Rigid head fixation was achieved by using cast material. Transfer of stereotactic coordinates was performed by an external positioning device. The accuracy during treatment planning was quantitatively assessed by using repeated computed tomography (CT) examinations in treatment position (reproducibility of isocenter). Linear discrepancies were measured between treatment plan and CT examination. In addition, for each patient, a series of 20 verifications were taken in orthogonal projections. Linear discrepancies were measured between first and all subsequent verifications (accuracy during treatment delivery). Results: For the total group of patients, the distribution of deviations during treatment setup showed mean values between -0.3-1.2 mm, with standard deviations (SD) of 1.3-2.0 mm. During treatment delivery, the distribution of deviations revealed mean values between 0.7-0.8 mm, with SDs of 0.5-0.6 mm, respectively. For all patients, deviations for the transition to the treatment machine were similar to deviations during subsequent treatment delivery, with 95% of all absolute deviations between less than 2.8 and 4.6 mm. Conclusion: Random fluctuations of field displacements during treatment planning and delivery prevail. Therefore, our quantitative data should be considered when prescribing the safety margins of the planning target volume. Repeated CT examination are useful to detect operator errors and large random or systematic deviations before start of treatment. Control procedures during treatment delivery appear to be of limited importance. In addition, our findings should help to
International Nuclear Information System (INIS)
Taghian, Alphonse G.; Kozak, Kevin R.; Doppke, Karen P.; Katz, Angela; Smith, Barbara L.; Gadd, Michele; Specht, Michelle; Hughes, Kevin; Braaten, Kristina; Kachnic, Lisa A.; Recht, Abram; Powell, Simon N.
2006-01-01
Purpose: Several accelerated partial-breast irradiation (APBI) techniques are being investigated in patients with early-stage breast cancer. We present our initial experience using three-dimensional conformal radiation therapy (3D-CRT). Methods and Materials: Sixty-one patients with tumors of 2 cm or less and negative axillary nodes were treated with 3D-CRT accelerated partial-breast irradiation (APBI) between August 2003 and March 2005. The prescribed radiation dose was 32 Gy in 4-Gy fractions given twice daily. Efforts were made to minimize the number of beams required to achieve adequate planning target volume (PTV) coverage. Results: A combination of photons and electrons was used in 85% of patients. A three-field technique that consisted of opposed, conformal tangential photons and enface electrons was employed in 43 patients (70%). Nine patients (15%) were treated with a four-field arrangement, which consisted of three photon fields and enface electrons. Mean PTV volumes that received 100%, 95%, and 90% of the prescribed dose were 93% ± 7%, 97% ± 4%, and 98% ± 2%, respectively. Dose inhomogeneity exceeded 10% in only 7 patients (11%). Mean doses to the ipsilateral lung and heart were 1.8 Gy and 0.8 Gy, respectively. Conclusions: Simple 3D-CRT techniques of APBI can achieve appropriate PTV coverage while offering significant normal-tissue sparing. Therefore, this noninvasive approach may increase the availability of APBI to patients with early-stage breast cancer
Indecomposability parameters in chiral logarithmic conformal field theory
International Nuclear Information System (INIS)
Vasseur, Romain; Jacobsen, Jesper Lykke; Saleur, Hubert
2011-01-01
Work of the last few years has shown that the key algebraic features of Logarithmic Conformal Field Theories (LCFTs) are already present in some finite lattice systems (such as the XXZ spin-1/2 chain) before the continuum limit is taken. This has provided a very convenient way to analyze the structure of indecomposable Virasoro modules and to obtain fusion rules for a variety of models such as (boundary) percolation etc. LCFTs allow for additional quantum numbers describing the fine structure of the indecomposable modules, and generalizing the 'b-number' introduced initially by Gurarie for the c=0 case. The determination of these indecomposability parameters (or logarithmic couplings) has given rise to a lot of algebraic work, but their physical meaning has remained somewhat elusive. In a recent paper, a way to measure b for boundary percolation and polymers was proposed. We generalize this work here by devising a general strategy to compute matrix elements of Virasoro generators from the numerical analysis of lattice models and their continuum limit. The method is applied to XXZ spin-1/2 and spin-1 chains with open (free) boundary conditions. They are related to gl(n+m|m) and osp(n+2m|2m)-invariant superspin chains and to non-linear sigma models with supercoset target spaces. These models can also be formulated in terms of dense and dilute loop gas. We check the method in many cases where the results were already known analytically. Furthermore, we also confront our findings with a construction generalizing Gurarie's, where logarithms emerge naturally in operator product expansions to compensate for apparently divergent terms. This argument actually allows us to compute indecomposability parameters in any logarithmic theory. A central result of our study is the construction of a Kac table for the indecomposability parameters of the logarithmic minimal models LM(1,p) and LM(p,p+1).
Non-singular string-cosmologies from exact conformal field theories
International Nuclear Information System (INIS)
Vega, H.J. de; Larsen, A.L.; Sanchez, N.
2001-01-01
Non-singular two and three dimensional string cosmologies are constructed using the exact conformal field theories corresponding to SO(2,1)/SO(1,1) and SO(2,2)/SO(2,1). All semi-classical curvature singularities are canceled in the exact theories for both of these cosets, but some new quantum curvature singularities emerge. However, considering different patches of the global manifolds, allows the construction of non-singular space-times with cosmological interpretation. In both two and three dimensions, we construct non-singular oscillating cosmologies, non-singular expanding and inflationary cosmologies including a de Sitter (exponential) stage with positive scalar curvature as well as non-singular contracting and deflationary cosmologies. Similarities between the two and three dimensional cases suggest a general picture for higher dimensional coset cosmologies: Anisotropy seems to be a generic unavoidable feature, cosmological singularities are generically avoided and it is possible to construct non-singular cosmologies where some spatial dimensions are experiencing inflation while the others experience deflation
Development of model plans in three dimensional conformal radiotherapy for brain tumors
International Nuclear Information System (INIS)
Pyo, Hongryull; Kim, Gwieon; Keum, Kichang; Chang, Sekyung; Suh, Changok; Lee, Sanghoon
2002-01-01
Three dimensional conformal radiotherapy planning is being used widely for the treatment of patients with brain tumor. However, it takes much time to develop an optimal treatment plan, therefore, it is difficult to apply this technique to all patients. To increase the efficiency of this technique, we need to develop standard radiotherapy plans for each site of the brain. Therefore we developed several 3 dimensional conformal radiotherapy plans (3D plans) for tumors at each site of brain, compared them with each other, and with 2 dimensional radiotherapy plans. Finally model plans for each site of the brain were decided. Imaginary tumors, with sizes commonly observed in the clinic, were designed for each site of the brain and drawn on CT images. The planning target volumes (PTVs) were as follows; temporal tumor-5.7 x 8.2 x 7.6 cm, suprasellar tumor-3 x 4 x 4.1 cm, thalamic tumor-3.1 x 5.9 x 3.7 cm, frontoparietal tumor-5.5 x 7 x 5.5 cm, and occipitoparietal tumor-5 x 5.5 x 5 cm. Plans using parallel opposed 2-portals and/or 3 portals including fronto-vertex and 2 lateral fields were developed manually as the conventional 2D plans, and 3D noncoplanar conformal plans were developed using beam's eye view and the automatic block drawing tool. Total tumor dose was 54 Gy for a suprasellar tumor, 59.4 Gy and 72 Gy for the other tumors. All dose plans (including 2D plans) were calculated using 3D plan software. Developed plans were compared with each other using dose-volume histograms (DVH), normal tissue complication probabilities (NTCP) and variable dose statistic values (minimum, maximum and mean dose, D5, V83, V85 and V95). Finally a best radiotherapy plan for each site of brain was selected. 1) Temporal tumor; NTCPs and DVHs of the normal tissue of all 3D plans were superior to 2D plans and this trend was more definite when total dose was escalated to 72 Gy (NTCPs of normal brain 2D plans: 27%, 8% → 3D plans: 1%, 1%). Various dose statistic values did not show any
International Nuclear Information System (INIS)
Hsu, Wei-Chung; Chung, Na-Na; Wang, Po-Ming; Ying, Kung-Shih; Shin, Jeng-Shiann; Chao, Che-Jen; Lin, Gau-De; Chan, Sue-Ching; Ting, Lai-Lei
2006-01-01
The purpose of this study was to evaluate the effectiveness of three-dimensional conformal radiotherapy and thalidomide in the treatment of advanced hepatocellular carcinoma. Between 1999 and 2003, 121 patients (mean age, 54.4±12.4 years; range, 20-81 years) with advanced hepatocellular carcinoma received three-dimensional conformal radiotherapy and thalidomide. Radiation was delivered in 1.5 Gy fractions twice daily for 5 days a week, for a total dose of 45-75 Gy. Mean treatment volume was 429.52±408.50 cm 3 (range, 26.89-2284.82 cm 3 ). Thalidomide was given concomitantly: 200 mg/day in 109 patients, 300 mg/day in 8 patients and 400 mg/day in 4 patients. Treatment responses, survival rates and factors affecting survival were analyzed. Treatment responses were observed in 61% of the patients. Liver cirrhosis (P=0.001) and tumor size (P=0.001) significantly affected the tumor responses. Overall survival at 6, 12 and 24 months was 84.8, 60.0 and 44.6%, respectively. On univariate analysis, liver cirrhosis (P=0.003), Karnofsky performance status (P=0.007), tumor size (P<0.001), portal vein tumor thrombosis (P<0.001) and alpha-fetoprotein level (P=0.003) were shown to significantly affect survival. On multivariate analysis, only thrombosis (P=0.039) and alpha-fetoprotein level (P=0.006) were shown to be factors affecting survival. Three-dimensional conformal radiotherapy with thalidomide seems to be effective in the treatment of advanced hepatocellular carcinoma. (author)
SU-E-T-279: Realization of Three-Dimensional Conformal Dose Planning in Prostate Brachytherapy
Energy Technology Data Exchange (ETDEWEB)
Li, Z; Jiang, S; Yang, Z [Tianjin University, Tianjin (China); Bai, H; Zhang, X [Seeds biological Pharmacy Ltd, Tianjin (China)
2014-06-01
Purpose: Successful clinical treatment in prostate brachytherapy is largely dependent on the effectiveness of pre-surgery dose planning. Conventional dose planning method could hardly arrive at a satisfy result. In this abstract, a three-dimensional conformal localized dose planning method is put forward to ensure the accuracy and effectiveness of pre-implantation dose planning. Methods: Using Monte Carlo method, the pre-calculated 3-D dose map for single source is obtained. As for multiple seeds dose distribution, the maps are combined linearly to acquire the 3-D distribution. The 3-D dose distribution is exhibited in the form of isodose surface together with reconstructed 3-D organs group real-timely. Then it is possible to observe the dose exposure to target volume and normal tissues intuitively, thus achieving maximum dose irradiation to treatment target and minimum healthy tissues damage. In addition, the exfoliation display of different isodose surfaces can be realized applying multi-values contour extraction algorithm based on voxels. The needles could be displayed in the system by tracking the position of the implanted seeds in real time to conduct block research in optimizing insertion trajectory. Results: This study extends dose planning from two-dimensional to three-dimensional, realizing the three-dimensional conformal irradiation, which could eliminate the limitations of 2-D images and two-dimensional dose planning. A software platform is developed using VC++ and Visualization Toolkit (VTK) to perform dose planning. The 3-D model reconstruction time is within three seconds (on a Intel Core i5 PC). Block research could be conducted to avoid inaccurate insertion into sensitive organs or internal obstructions. Experiments on eight prostate cancer cases prove that this study could make the dose planning results more reasonable. Conclusion: The three-dimensional conformal dose planning method could improve the rationality of dose planning by safely reducing
Sine-square deformation of solvable spin chains and conformal field theories
International Nuclear Information System (INIS)
Katsura, Hosho
2012-01-01
We study solvable spin chains, one-dimensional massless Dirac fermions and conformal field theories (CFTs) with sine-square deformation (SSD), in which the Hamiltonian density is modulated by the function f(x) = sin 2 (πx/ℓ), where x is the position and ℓ is the length of the system. For the XY chain and the transverse field Ising chain at criticality, it is shown that the ground state of an open system with SSD is identical to that of a uniform chain with periodic boundary conditions. The same holds for the massless Dirac fermions with SSD, corresponding to the continuum limit of the gapless XY chain. For general CFTs, we find that the Hamiltonian of a system with SSD has an expression in terms of the generators of the Virasoro algebra. This allows us to show that the vacuum state is an exact eigenstate of the sine-square deformed Hamiltonian. Furthermore, for a restricted class of CFTs associated with affine Lie (Kac–Moody) algebras, including c = 1 Gaussian CFT, we prove that the vacuum is an exact ground state of the deformed Hamiltonian. This explains why the SSD has succeeded in suppressing boundary effects in one-dimensional critical systems, as observed in previous numerical studies. (paper)
General solution of an exact correlation function factorization in conformal field theory
International Nuclear Information System (INIS)
Simmons, Jacob J H; Kleban, Peter
2009-01-01
The correlation function factorization with K a boundary operator product expansion coefficient, is known to hold for certain scaling operators at the two-dimensional percolation point and in a few other cases. Here the correlation functions are evaluated in the upper half-plane (or any conformally equivalent region) with x 1 and x 2 arbitrary points on the real axis, and z an arbitrary point in the interior. This type of result is of interest because it is both exact and universal, relates higher-order correlation functions to lower-order ones and has a simple interpretation in terms of cluster or loop probabilities in several statistical models. This motivated us to use the techniques of conformal field theory to determine the general conditions for its validity. Here, we discover that either (see display) factorizes in this way for any central charge c, generalizing previous results. In particular, the factorization holds for either FK (Fortuin–Kasteleyn) or spin clusters in the Q-state Potts models; it also applies to either the dense or dilute phases of the O(n) loop models. Further, only one other non-trivial set of highest-weight operators (in an irreducible Verma module) factorizes in this way. In this case the operators have negative dimension (for c<1) and do not seem to have a physical realization
A new class of conformal field theories with anomalous dimensions
International Nuclear Information System (INIS)
Itou, Etsuko
2004-01-01
We find a class of fixed point theory for 2- and 3-dimensional non-linear sigma models using Wilsonian renormalization group (WRG) approach. In 2-dimensional case, the fixed point theory is equivalent to the Witten's semi-infinite cigar model. In 3-dimensional case, the theory has one parameter which describes a marginal deformation from the infrared to ultraviolet fixed points of the CP N model in the theory spaces. (author)
Estimate of the damage in organs induced by neutrons in three-dimensional conformal radiotherapy
International Nuclear Information System (INIS)
Benites R, J. L.; Vega C, H. R.; Uribe, M. del R.
2014-08-01
By means of Monte Carlo methods was considered the damage in the organs, induced by neutrons, of patients with cancer that receive treatment in modality of three-dimensional conformal radiotherapy (3D-CRT) with lineal accelerator Varian Ix. The objective of this work was to estimate the damage probability in radiotherapy patients, starting from the effective dose by neutrons in the organs and tissues out of the treatment region. For that a three-dimensional mannequin of equivalent tissue of 30 x 100 x 30 cm 3 was modeled and spherical cells were distributed to estimate the Kerma in equivalent tissue and the absorbed dose by neutrons. With the absorbed dose the effective dose was calculated using the weighting factors for the organ type and radiation type. With the effective dose and the damage factors, considered in the ICRP 103, was considered the probability of damage induction in organs. (Author)
Oda, Akifumi; Fukuyoshi, Shuichi
2015-06-01
The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.
A new tool in the classification of rational conformal field theories
International Nuclear Information System (INIS)
Christe, P.; Ravanini, F.
1988-10-01
The fact that in any rational conformal field theory (RCFT) 4-point functions on the sphere must satisfy an ordinary differential equation gives a simple condition on the conformal dimensions of primary fields. We discuss how this can help in the classification program of RCFT. As an example all associative fusion rules with less than four non-trivial primary fields and N ijk <<1 are discussed. Another application to the classification of chiral algebras is briefly mentioned. (orig.)
24 +24 real scalar multiplet in four dimensional N =2 conformal supergravity
Hegde, Subramanya; Lodato, Ivano; Sahoo, Bindusar
2018-03-01
Starting from the 48 +48 component multiplet of supercurrents for a rigid N =2 tensor multiplet in four spacetime dimensions, we obtain the transformation of the linearized supergravity multiplet which couples to this supercurrent multiplet. At the linearized level, this 48 +48 component supergravity multiplet decouples into the 24 +24 component linearized standard Weyl multiplet and a 24 +24 component irreducible matter multiplet containing a real scalar field. By a consistent application of the supersymmetry algebra with field-dependent structure constants appropriate to N =2 conformal supergravity, we find the full transformation law for this multiplet in a conformal supergravity background. By performing a suitable field redefinition, we find that the multiplet is a generalization of the flat space multiplet, obtained by Howe et al. in Nucl. Phys. B214, 519 (1983), 10.1016/0550-3213(83)90249-3, to a conformal supergravity background. We also present a set of constraints which can be consistently imposed on this multiplet to obtain a restricted minimal 8 +8 off-shell matter multiplet. We also show, as an example, the precise embedding of the tensor multiplet inside this multiplet.
International Nuclear Information System (INIS)
Lu Jie; Zhang Guifang; Bai Tong; Yin Yong; Fan Tingyong; Wu Chaoxia
2009-01-01
Objective: To investigate the dosimetry advantages of intensity modulated radiotherapy (IMRT)of brain glioma compared with that of three-dimensional conformal radiotherapy (SD CRT). Methods: Ten patients with brain glioma were enrolled in this study. Three-dimensional conf0rmal and intensity modulated radiotherapy plans were performed for each patient. The dose distributions of target volume and normal tissues, conformal index (CI) and heterogeneous index (HI) were analyzed using the dose-volume histogram (DVH). The prescription dose was 60 Gy in 30 fractions. Results: IMRT plans decrease the maximum dose and volume of brainstem, mean dose of affected side parotid and maximum dose of spinal-cord. The CI for PTV of IMRT was superior to that of SD CRT, the HI for PTV has no statistical significance of the two model plans. Conclusions: IMRT plans can obviously decrease the dose and volume of brainstem. IMRT is a potential method in the treatment of brain glioma, and dose escalation was possible in patients with brain glioma. (authors)
International Nuclear Information System (INIS)
Zhu Yaqun; Tian Ye; Zhang Junning; Wang Bin
2010-01-01
Objective: To evaluate the compliance and efficacy of chemoradiotherapy for locally advanced (unresectable) rectal cancer. Methods: Thirty eight patients with locally advanced (T4 or recurred) rectal cancer received three dimensional-conformal radiotherapy (for 46 ∼ 50Gy/5 weeks and was boosted to the tumor 16 ∼ 18Gy/2 weeks, 2Gy/fraction, 5 days/week) in combination with capecitabine 1 650mg · m -2 · d -1 , day 1-14, every 3 weeks. Results: The overall response rate was 57.9%, with CR 5 (13.2%), PR 17(44.7%), SD 10 (26.3%), PD 6 (15.8%), median survival time, the 1-year overall survival rate and the 2-year overall survival rate were 18 months, 64.43%, 18.78%, respectively. The remission rate of pain and improvement rate of performance status were 100% and 52.8%. Treatment-related toxicity mainly showed at diarrhea, neutrocytopenia and hand-foot syndrome, the incidence of grade 3 toxicity were 15.8%, 15.8%, 7.9%, respectively. there were no grade 4 toxicity and treatment-related death. Conclusion: Combination of three dimensional-conformal radiotherapy with capecitabine is active in advanced rectal cancer, It is a well-tolerated regimen. (authors)
Virasoro conformal blocks and thermality from classical background fields
Energy Technology Data Exchange (ETDEWEB)
Fitzpatrick, A. Liam [Stanford Institute for Theoretical Physics, Stanford University,Via Pueblo, Stanford, CA 94305 (United States); SLAC National Accelerator Laboratory,Sand Hill Road, Menlo Park, CA 94025 (United States); Kaplan, Jared [Department of Physics and Astronomy, Johns Hopkins University,Charles Street, Baltimore, MD 21218 (United States); Walters, Matthew T. [Department of Physics, Boston University,Commonwealth Avenue, Boston, MA 02215 (United States)
2015-11-30
We show that in 2d CFTs at large central charge, the coupling of the stress tensor to heavy operators can be re-absorbed by placing the CFT in a non-trivial background metric. This leads to a more precise computation of the Virasoro conformal blocks between heavy and light operators, which are shown to be equivalent to global conformal blocks evaluated in the new background. We also generalize to the case where the operators carry U(1) charges. The refined Virasoro blocks can be used as the seed for a new Virasoro block recursion relation expanded in the heavy-light limit. We comment on the implications of our results for the universality of black hole thermality in AdS{sub 3}, or equivalently, the eigenstate thermalization hypothesis for CFT{sub 2} at large central charge.
Particles and energy fluxes from a conformal field theory perspective
International Nuclear Information System (INIS)
Fabbri, A.; Navarro-Salas, J.; Olmo, G.J.
2004-01-01
We analyze the creation of particles in two dimensions under the action of conformal transformations. We focus our attention on Mobius transformations and compare the usual approach, based on the Bogoliubov coefficients, with an alternative but equivalent viewpoint based on correlation functions. In the latter approach the absence of particle production under full Mobius transformations is manifest. Moreover, we give examples, using the moving-mirror analogy, to illustrate the close relation between the production of quanta and energy
Differential equation for genus-two characters in arbitrary rational conformal field theories
International Nuclear Information System (INIS)
Mathur, S.D.; Sen, A.
1989-01-01
We develop a general method for deriving ordinary differential equations for the genus-two ''characters'' of an arbitrary rational conformal field theory using the hyperelliptic representation of the genus-two moduli space. We illustrate our method by explicitly deriving the character differential equations for k=1 SU(2), G 2 , and F 4 WZW models. Our method provides an intrinsic definition of conformal field theories on higher genus Riemann surfaces. (orig.)
Conformal Field Theory as Microscopic Dynamics of Incompressible Euler and Navier-Stokes Equations
International Nuclear Information System (INIS)
Fouxon, Itzhak; Oz, Yaron
2008-01-01
We consider the hydrodynamics of relativistic conformal field theories at finite temperature. We show that the limit of slow motions of the ideal hydrodynamics leads to the nonrelativistic incompressible Euler equation. For viscous hydrodynamics we show that the limit of slow motions leads to the nonrelativistic incompressible Navier-Stokes equation. We explain the physical reasons for the reduction and discuss the implications. We propose that conformal field theories provide a fundamental microscopic viewpoint of the equations and the dynamics governed by them
Conformal field theory as microscopic dynamics of incompressible Euler and Navier-Stokes equations.
Fouxon, Itzhak; Oz, Yaron
2008-12-31
We consider the hydrodynamics of relativistic conformal field theories at finite temperature. We show that the limit of slow motions of the ideal hydrodynamics leads to the nonrelativistic incompressible Euler equation. For viscous hydrodynamics we show that the limit of slow motions leads to the nonrelativistic incompressible Navier-Stokes equation. We explain the physical reasons for the reduction and discuss the implications. We propose that conformal field theories provide a fundamental microscopic viewpoint of the equations and the dynamics governed by them.
Pelvic Ewing sarcomas. Three-dimensional conformal vs. intensity-modulated radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Mounessi, F.S.; Lehrich, P.; Haverkamp, U.; Eich, H.T. [Muenster Univ. (Germany). Dept. of Radiation Oncology; Willich, N. [Muenster Univ. (Germany). Dept. of Radiation Oncology; Universitaetsklinikum Muenster (Germany). RiSK - Registry for the Evaluation of Late Side Effects after Radiotherapy in Childhood and Adolescence; Boelling, T. [Center for Radiation Oncology, Osnabrueck (Germany)
2013-04-15
The goal of the present work was to assess the potential advantage of intensity-modulated radiotherapy (IMRT) over three-dimensional conformal radiotherapy (3D-CRT) planning in pelvic Ewing's sarcoma. A total of 8 patients with Ewing sarcoma of the pelvis undergoing radiotherapy were analyzed. Plans for 3D-CRT and IMRT were calculated for each patient. Dose coverage of the planning target volume (PTV), conformity and homogeneity indices, as well as further parameters were evaluated. Results The average dose coverage values for PTV were comparable in 3D-CRT and IMRT plans. Both techniques had a PTV coverage of V{sub 95} > 98 % in all patients. Whereas the IMRT plans achieved a higher conformity index compared to the 3D-CRT plans (conformity index 0.79 {+-} 0.12 vs. 0.54 {+-} 0.19, p = 0.012), the dose distribution across the target volumes was less homogeneous with IMRT planning than with 3D-CRT planning. This difference was statistically significant (homogeneity index 0.11 {+-} 0.03 vs. 0.07 {+-} 0.0, p = 0.035). For the bowel, D{sub mean} and D{sub 1%}, as well as V{sub 2} to V{sub 60} were reduced in IMRT plans. For the bladder and the rectum, there was no significant difference in D{sub mean}. However, the percentages of volumes receiving at least doses of 30, 40, 45, and 50 Gy (V{sub 30} to V{sub 50}) were lower for the rectum in IMRT plans. The volume of normal tissue receiving at least 2 Gy (V{sub 2}) was significantly higher in IMRT plans compared with 3D-CRT, whereas at high dose levels (V{sub 30}) it was significantly lower. Compared to 3D-CRT, IMRT showed significantly better results regarding dose conformity (p = 0.012) and bowel sparing at dose levels above 30 Gy (p = 0.012). Thus, dose escalation in the radiotherapy of pelvic Ewing's sarcoma can be more easily achieved using IMRT. (orig.)
Conformal field theory and 2D quantum gravity
International Nuclear Information System (INIS)
Distler, J.; Kawai, Hikaru
1989-01-01
Inspired by the recent work of Knizhnik, Polyakov and Zamolodchikov on the solution of 2D quantum gravity in the 'light cone' gauge, we present a proposal for solving the theory in the usual conformal gauge. Our results for the critical exponents of the theory agree with the genus-zero results of KPZ. Since our formalism naturally generalizes to higher-genus Riemann surfaces, we obtain the critical exponents for all genera. The corresponding results for the supersymmetric case are presented. We also show how to calculate correlation functions in these theories. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Gatti, M.; Bresciani, S.; Ponzone, R.; Panaia, R.; Salatino, A.; Stasi, M.; Gabriele, P. [IRCC, Candiolo (Italy)
2011-10-15
Full text of publication follows: Purpose.- To analyse the incidence and severity of acute and late normal tissue toxicity and cosmetic outcome using three - dimensional conformal radiotherapy to deliver accelerated partial breast irradiation. Patients and Methods.- 70 patients with stage I disease were treated with three-dimensional conformal radiotherapy for accelerated partial breast irradiation, in an approved protocol. The prescribed dose was 34 Gy in all patients delivered in 10 fractions over 5 consecutive days. On all CT scans gross tumor volume (GTV ) was defined around surgical clips. A 1.5 cm margin was added in order to account for clinical target volume (CTV) . A margin of 1 cm was added to CTI to define the planning target volume (PTV). The dose-volume constraints were followed in accordance with the specifications as dictated in the NSABP/RTOG protocol. After treatment, patients underwent a clinical and cosmetic evaluation every 3 months. Late toxicity was evaluated according to the RTOG grading schema. The cosmetic assessment was performed by the physicians using the controlateral untreated breast as the reference (Harvard scale). Results.- Median patient age was 66 years (range 51-80). Median follow-up was 15 months (range 6-46). Tumor size was < 10 mm in 33 patients (53%) and > 2 cm in 4(6%). The mean value of the ratio between the PTV and the whole ipsilateral breast volume was 38 % and the median percentage whole breast volume that received 95 % of prescribed dose was 34% (range 16%-55%). The rate of G1 and G2 acute skin toxicity was 28% and 2% respectively and the late toxicity was 17% (G1). G2 or greater toxicities were not observed. The most pronounced G1 late toxicity was subcutaneous fibrosis, developed in 3 patients. The cosmetic outcome was excellent in 83% and good in 17%. Conclusion.- Accelerated partial breast irradiation using three-dimensional conformal radiotherapy is technically feasible with very low acute and late toxicity. Long
International Nuclear Information System (INIS)
Gatti, M.; Bresciani, S.; Ponzone, R.; Panaia, R.; Salatino, A.; Stasi, M.; Gabriele, P.
2011-01-01
Full text of publication follows: Purpose.- To analyse the incidence and severity of acute and late normal tissue toxicity and cosmetic outcome using three - dimensional conformal radiotherapy to deliver accelerated partial breast irradiation. Patients and Methods.- 70 patients with stage I disease were treated with three-dimensional conformal radiotherapy for accelerated partial breast irradiation, in an approved protocol. The prescribed dose was 34 Gy in all patients delivered in 10 fractions over 5 consecutive days. On all CT scans gross tumor volume (GTV ) was defined around surgical clips. A 1.5 cm margin was added in order to account for clinical target volume (CTV) . A margin of 1 cm was added to CTI to define the planning target volume (PTV). The dose-volume constraints were followed in accordance with the specifications as dictated in the NSABP/RTOG protocol. After treatment, patients underwent a clinical and cosmetic evaluation every 3 months. Late toxicity was evaluated according to the RTOG grading schema. The cosmetic assessment was performed by the physicians using the controlateral untreated breast as the reference (Harvard scale). Results.- Median patient age was 66 years (range 51-80). Median follow-up was 15 months (range 6-46). Tumor size was 2 cm in 4(6%). The mean value of the ratio between the PTV and the whole ipsilateral breast volume was 38 % and the median percentage whole breast volume that received 95 % of prescribed dose was 34% (range 16%-55%). The rate of G1 and G2 acute skin toxicity was 28% and 2% respectively and the late toxicity was 17% (G1). G2 or greater toxicities were not observed. The most pronounced G1 late toxicity was subcutaneous fibrosis, developed in 3 patients. The cosmetic outcome was excellent in 83% and good in 17%. Conclusion.- Accelerated partial breast irradiation using three-dimensional conformal radiotherapy is technically feasible with very low acute and late toxicity. Long-term results are needed to assess
Tolerance and early outcome results of postprostatectomy three-dimensional conformal radiotherapy
International Nuclear Information System (INIS)
Zelefsky, Michael J.; Aschkenasy, Eric; Kelsen, Suzanne; Leibel, Steven A.
1997-01-01
Purpose: Three-dimensional conformal radiotherapy (3D-CRT) has been associated with a reduction in acute and late toxicity among patients treated for localized prostatic cancer. The purpose of this study is to assess the acute and late toxicity of 3D-CRT delivered to patients in the postprostatectomy setting and to analyze which factors predict for durable biochemical control in this group of patients. Methods and Materials: Between 1988 and 1994, 42 patients were treated after prostatectomy with three-dimensional conformal radiotherapy. The median time from prostatectomy to radiotherapy was 11 months. Indications for treatment included a rising serum PSA level in 28 patients (65%) and positive surgical margins without a rising PSA level in 14 (35%). Twenty-five patients (60%) had pathologic stage T3 disease, and 32 (74%) had tumor at or close to the surgical margins. The median dose was 64.8 Gy, and the median follow-up time was 2 years. Results: 3D-CRT in the postprostatectomy setting was well tolerated. Three patients (7%) experienced Grade II acute genitourinary toxicity and nine patients (21%) experienced Grade II acute gastrointestinal toxicity during treatment. No patient experienced Grade III or higher acute morbidity. The 2-year actuarial risk for Grade II late genitourinary and gastrointestinal late complications were 5 and 9%, respectively. In patients with existing incontinence, the incidence of worsening stress incontinence 6 months after treatment was 17%, which resolved within 12 months to its preradiotherapy level in four of six cases (66%). The overall 2-year postirradiation PSA relapse-free survival rate was 53%. The 2-year PSA relapse-free survival was 66% for patients with undetectable PSA levels in the immediate postoperative period compared to 26% for those with detectable levels of PSA after surgery (p 1.0 ng/ml (p 1 ng/ml (p < 0.002) was the most important covariate predicting for a rising PSA after radiotherapy. Conclusions: After
International Nuclear Information System (INIS)
Vijayakumar, Srinivasan; Chen, George T.Y.
1995-01-01
Purpose: To briefly review scientific rationale of 3D conformal radiation therapy (3DCRT) and discuss the prospects, opportunities, and challenges in the implementation of 3DCRT. Some of these ideas were discussed during a workshop on 'Implementation of Three-Dimensional Conformal Radiation Therapy' in April 1994 at Bethesda, MD, and others have been discussed elsewhere in the literature. Methods and Materials: Local-regional control of cancer is an important component in the overall treatment strategy in any patient with cancer. It has been shown that failure to achieve local-regional control can lead to (a) an increase in chances of distant metastases, and (b) a decrease in the survival. In many disease sites, the doses delivered currently are inadequate to achieve satisfactory local tumor control rates; this is because in many sites, only limited doses of radiotherapy can be delivered due to the proximity of cancer to radiosensitive normal tissues. By conforming the radiotherapy beams to the tumor, doses to the tumors can be enhanced and doses to the normal tissues can be reduced. With the advances in 3DCRT, such conformation is possible now and is the rationale for using 3DCRT. However, a number of questions do remain that are not limited to the following: (a) What are the implications in terms of target volume definitions when implementing 3DCRT? (b) Are there some sites where research efforts can be focused to document the efficacy and cost effectiveness of 3DCRT? (c) How do we implement day-to-day 3DCRT treatment efficiently? (d) How do we transfer the technology from the university centers to the community without compromising quality? (e) What are all the quality assurance/quality improvement questions that need to be addressed and how do we ascertain quality assurance of 3DCRT? (f) Have we looked at cost-benefit ratios and quality of life (QOL) issues closely? Results: There is a need for defining multiple target volumes: gross tumor volume, clinical
International Nuclear Information System (INIS)
Kim, Dae Woong; Kim, Jong Won; Choi, Yun Kyeong; Kim, Jung Soo; Hwang, Jae Woong; Jeong, Kyeong Sik; Choi, Gye Suk
2008-01-01
The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. In this paper, we comparing the dose distribution between three dimensional conformal radiation radiotherapy (3D-CRT) and helical tomotherapy (TOMO) plan for partial breast cancer. Twenty patients were included in the study, and plans for two techniques were developed for each patient (left breast:10 patients, right breast:10 patients). For each patient 3D-CRT planning was using pinnacle planning system, inverse plan was made using Tomotherapy Hi-Art system and using the same targets and optimization goals. We comparing the Homogeneity index (HI), Conformity index (CI) and sparing of the organs at risk for dose-volume histogram. Whereas the HI, CI of TOMO was significantly better than the other, 3D-CRT was observed to have significantly poorer HI, CI. The percentage ipsilateral non-PTV breast volume that was delivered 50% of the prescribed dose was 3D-CRT (mean: 40.4%), TOMO (mean: 18.3%). The average ipsilateral lung volume percentage receiving 20% of the PD was 3D-CRT (mean: 4.8%), TOMO (mean: 14.2), concerning the average heart volume receiving 20% and 10% of the PD during treatment of left breast cancer 3D-CRT (mean: 1.6%, 3.0%), TOMO (mean: 9.7%, 26.3%) In summary, 3D-CRT and TOMO techniques were found to have acceptable PTV coverage in our study. However, in TOMO, high conformity to the PTV and effective breast tissue sparing was achieved at the expense of considerable dose exposure to the lung and heart.
Three-dimensional conformal radiation therapy: the tomo-therapy approach
International Nuclear Information System (INIS)
Linthout, N.; Verellen, D.; Coninck, P. de; Bel, A.; Storme, G.
2000-01-01
Conformal radiation therapy allows the possibility of delivering high doses at the tumor volume whilst limiting the dose to the surrounding tissues and diminishing the secondary effects. With the example of the conformal radiation therapy used at the AZ VU8 (3DCRT and tomo-therapy), two treatment plans of a left ethmoid carcinoma will be evaluated and discussed in detail. The treatment of ethmoid cancer is technically difficult for both radiation therapy and surgery because of the anatomic constraints and patterns of local spread. A radiation therapy is scheduled to be delivered after surgical resection of the tumor. The treatment plan for the radiation therapy was calculated on a three-dimensional (3D) treatment planning system based on virtual simulation with a beam's eye view: George Sherouse's Gratis. An effort was made to make the plan as conformal and as homogeneous as possible to deliver a dose of 66 Gy in 33 fractions at the tumor bed with a maximum dose of 56 Gy to the right optic nerve and the chiasma. To establish the clinical utility and potential advantages of tomo-therapy over 3DCRT for ethmoid carcinoma, the treatment of this patient was also planned with Peacock Plant. For both treatment plans the isodose distributions and cumulative dose volume histograms (CDVH) were computed. Superimposing the CDVHs yielded similar curves for the target and an obvious improvement for organs at risk such as the chiasma, brainstem and the left eye when applying tomo-therapy. These results have also been reflected in the tumor control probabilities (equal for both plans) and the normal tissue complication probabilities (NTCP), yielding significant reductions in NTCP for tomo-therapy. The probability of uncomplicated tumor control was 52.7% for tomo-therapy against 38.3% for 3DCRT. (authors)
Method to planarize three-dimensional structures to enable conformal electrodes
Nikolic, Rebecca J; Conway, Adam M; Graff, Robert T; Reinhardt, Catherine; Voss, Lars F; Shao, Qinghui
2012-11-20
Methods for fabricating three-dimensional PIN structures having conformal electrodes are provided, as well as the structures themselves. The structures include a first layer and an array of pillars with cavity regions between the pillars. A first end of each pillar is in contact with the first layer. A segment is formed on the second end of each pillar. The cavity regions are filled with a fill material, which may be a functional material such as a neutron sensitive material. The fill material covers each segment. A portion of the fill material is etched back to produce an exposed portion of the segment. A first electrode is deposited onto the fill material and each exposed segment, thereby forming a conductive layer that provides a common contact to each the exposed segment. A second electrode is deposited onto the first layer.
Exact critical properties of two-dimensional polymer networks from conformal invariance
International Nuclear Information System (INIS)
Duplantier, B.
1988-03-01
An infinity of exact critical exponents for two-dimensional self-avoiding walks can be derived from conformal invariance and Coulomb gas techniques applied to the O(n) model and to the Potts model. They apply to polymer networks of any topology, for which a general scaling theory is given, valid in any dimension d. The infinite set of exponents has also been calculated to O(ε 2 ), for d=4-ε. The 2D study also includes other universality classes like the dense polymers, the Hamiltonian walks, the polymers at their θ-point. Exact correlation functions can be further given for Hamiltonian walks, and exact winding angle probability distributions for the self-avoiding walks
International Nuclear Information System (INIS)
Cavinato, Christianne C.; Campos, Leticia L.; Souza, Benedito H.; Carrete Junior, Henrique; Daros, Kellen A.C.; Medeiros, Regina B.; Giordani, Adelmo J.
2011-01-01
This work aims to compare the dose-response of the Fricke xylenol gel (FXG) dosimeter developed at IPEN using 270 Bloom gelatin from porcine skin made in Brazil evaluated using the magnetic resonance imaging (MRI) technique with the dosimetric response evaluated using the optical absorption (OA) spectrophotometry technique, in order to verify the possibility of quality assurance (QA) and reproducibility of FXG dosimeter to be carried out routinely using the OA technique for three-dimensional conformal radiotherapy (3DCRT) application using a 6 MV photons linear accelerator. The response in function of the absorbed dose of FXG dosimeter developed at IPEN presents linear behavior in clinical interest dose range when irradiated with Co-60 gamma radiation and 6 MV photons and evaluated using the MRI and OA techniques. The results indicate that the optical technique can be used for QA of FXG dosemeter when used in the possible application in QA of 3DCRT. (author)
Energy Technology Data Exchange (ETDEWEB)
Cavinato, Christianne C.; Campos, Leticia L., E-mail: ccavinato@ipen.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Souza, Benedito H.; Carrete Junior, Henrique; Daros, Kellen A.C.; Medeiros, Regina B., E-mail: bhsouza@unifesp.b, E-mail: daros.kellen@unifesp.b, E-mail: rbitel-li.ddi@epm.b [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Dept. de Diagnostico por Imagem; Giordani, Adelmo J. [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Servico de Radioterapia
2011-07-01
This work aims to compare the dose-response of the Fricke xylenol gel (FXG) dosimeter developed at IPEN using 270 Bloom gelatin from porcine skin made in Brazil evaluated using the magnetic resonance imaging (MRI) technique with the dosimetric response evaluated using the optical absorption (OA) spectrophotometry technique, in order to verify the possibility of quality assurance (QA) and reproducibility of FXG dosimeter to be carried out routinely using the OA technique for three-dimensional conformal radiotherapy (3DCRT) application using a 6 MV photons linear accelerator. The response in function of the absorbed dose of FXG dosimeter developed at IPEN presents linear behavior in clinical interest dose range when irradiated with Co-60 gamma radiation and 6 MV photons and evaluated using the MRI and OA techniques. The results indicate that the optical technique can be used for QA of FXG dosemeter when used in the possible application in QA of 3DCRT. (author)
International Nuclear Information System (INIS)
Radaideh, K.M.; Matalqah, L.M.; Matalqah, L.M.; Tajuddin, A.A.; Luen, F.W.L.; Bauk, S.; Abdel Munem, E.M.E.
2012-01-01
The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg, Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5 %. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3 %. The phantom's preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification. (author)
International Nuclear Information System (INIS)
Neumann, J.M.; Macquaire, F.
1991-01-01
This report presents the elementary bases for an initiation to the conformational study of peptides and proteins by using two-dimensional proton NMR experiments. First, some general features of protein structures are summarized. A second chapter is devoted to the basic NMR experiments and to the spectral parameters which provide a structural information. This description is illustrated by NMR spectra of peptides. The third chapter concerns the most standard two-dimensional proton NMR experiments and their use for a conformational study of peptides and proteins. Lastly, an example of NMR structural investigation of a peptide is reported [fr
Novel solution conformation of DNA observed in d(GAATTCGAATTC) by two-dimensional NMR spectroscopy
International Nuclear Information System (INIS)
Chary, K.V.R.; Hosur, R.V.; Govil, G.; Zu-kun, T.; Miles, H.T.
1987-01-01
Resonance assignments of nonexchangeable base and sugar protons of the self-complementary dodecanucleotide d(GAATTCGAATTC) have been obtained by using the two-dimensional Fourier transform NMR methods correlated spectroscopy and nuclear Overhauser effect spectroscopy. Conformational details about the sugar pucker, the glycosidic dihedral angle, and the overall secondary structure of the molecule has been derived from the relative intensities of cross peaks in the two-dimensional NMR spectra in aqueous solution. It is observed that d(GAATTCGAATTC) assumes a novel double-helical structure. The solution conformations of the two complementary strands are identical, unlike those observed in a related sequence in the solid state. Most of the five-membered sugar rings adopt an unusual O1'-endo geometry. All the glycosidic dihedral angles are in the anti domain. The AATT segments A2-T5 and A8-T11 show better stacking compared to the rest of the molecule. These features fit into a right-handed DNA model for the above two segments, with the sugar geometries different from the conventional ones. There are important structural variations in the central TCG portion, which is known to show preferences for DNase I activity, and between G1-A2 and G7-A8, which are cleavage points in the EcoRI recognition sequence. The sugar puckers for G1 and G7 are significantly different from the rest of the molecule. Further, in the three segments mentioned above, the sugar phosphate geometry is such that the distances between protons on adjacent nucleotides are much larger than those expected for a right-handed DNA. The authors suggest that such crevices in the DNA structure may act as hot points in initiation of protein recognition
International Nuclear Information System (INIS)
Caudrelier, J.M.; Auliard, A.; Sarrazin, T.; Gibon, D.; Coche-Dequeant, B.; Castelain, B.
2001-01-01
Comparison between conventional and three-dimensional conformal treatment planning for radiotherapy of cerebral tumors. Purpose. - We prospectively compared a conventional treatment planning (PT2D) and 3-dimensional conformal treatment planning (PT3D) for radiotherapy of cerebral tumours. Patients and methods.- Patients treated between 1/10/98 and 1/4/99 by irradiation for cerebral tumours were analysed. For each case, we planned PT2D using conventional orthogonal x-ray films, and afterward, PT3D using CT scan. Gross tumor volume, planning target volume and normal tissue volumes were defined. Dose was prescribed according to report 50 of the International Commission on Radiation Units and Measurements (ICRU). We compared surfaces of sagittal view targets defined on PT2D and PT3D and called them S2D and S3D, respectively. Irradiated volumes by 90% isodoses (VE-90%) and normal tissue volumes irradiated by 20, 50, 90% isodoses were calculated and compared using Student's paired t-test. Results. -There was a concordance of 84% of target surfaces defined on PT2D and PT3D. Percentages of target surface under- or-over defined by PT2D were 16 and 13% respectively. VE-90% was decreased by 15% (p = 0.07) with PT3D. Normal brain volume irradiated by 90% isodose was decreased by 27% with PT3D (p = 0.04). Conclusion.- For radiotherapy of cerebral tumors using only coplanar beams, PT3D leads to a reduction of normal brain tissue irradiated. We recommend PT3D for radiotherapy of cerebral tumors, particularly for low-grade or benign tumors (meningiomas, neuromas, etc.). (authors)
Therapeutic effect analysis of three dimensional conformal radiotherapy non-small cell lung cancer
International Nuclear Information System (INIS)
Yao Zhijun; Cao Yongzhen; Zhang Wenxue; Liang Feng
2012-01-01
Objective: To analyse the treatment effect of non-small cell lung cancer of three dimensional conformal radiotherapy (3D-CRT) and to study the effect of patient survival related factors. Methods: Retrospective analysis was mack for 136 cases of non-small cell lung cancer, all accept 3D-CRT, through the case data collection and long-term follow-up, using the single factor and multiple factor analysis survival time and its influencing factors. Results: The recent curative effects of 136 cases of patients with three dimensional conformal radiotherapy: Complete response (CR) 14.7% (20/136), partial response (PR) 60.3 (82/136), stable disease(SD) 19.9% (27/136), progression disease (PD) 5.1% (7/136), total effective rate is 75% (102/136). One, two, three, five year survival rate is 79.4%, 45.4%, 22.1%, 12.5%. Side effects: Class 1 radiated esophagitis 35 cases, Class 2 radiated esophagitis 16 cases, Class 3 and above radiated esophagitis 0 case. Class I radiated pneumonia 20 cases, Class 2 radiated pneumonia 9 cases, Class 3 radiated pneumonia 0 case. Single factor analysis shows the influence of gender, age, pathology, phase, dose, and first-phase curative effect to the survival time are of a statistical significance, Multiple factor analysis showed KPS score, phase, dose, first-phase curative effect are the survival time independent factors. Conclusion: 3D-CRT for patients with non-small cell lung carcinoma is a safe, effective treatment method, Side effects are relatively low, and the patients survival time is long after radiotherapy. (authors)
International Nuclear Information System (INIS)
Baseilhac, P.; Fateev, V.A.
1998-01-01
We calculate the vacuum expectation values of local fields for the two-parameter family of integrable field theories introduced and studied by Fateev (1996). Using this result we propose an explicit expression for the vacuum expectation values of local operators in parafermionic sine-Gordon models and in integrable perturbed SU(2) coset conformal field theories. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Lee, Nancy Y. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States). Radiation Oncology; Lu, Jiade J. (eds.) [National Univ. Health System, Singapore (Singapore). Dept. of Radiation Oncology; National Univ. of Singapore (Singapore). Dept. of Medicine
2013-03-01
Practical handbook on selection and delineation of tumor volumes and fields for conformal radiation therapy, including IMRT. Helpful format facilitating use on a step-by-step basis in daily practice. Designed to ensure accurate coverage of commonly encountered tumors along their routes of spread. This handbook is designed to enable radiation oncologists to appropriately and confidently delineate tumor volumes/fields for conformal radiation therapy, including intensity-modulated radiation therapy (IMRT), in patients with commonly encountered cancers. The orientation of this handbook is entirely practical, in that the focus is on the illustration of clinical target volume (CTV) delineation for each major malignancy. Each chapter provides guidelines and concise knowledge on CTV selection for a particular disease, explains how the anatomy of lymphatic drainage shapes the selection of the target volume, and presents detailed illustrations of volumes, slice by slice, on planning CT images. While the emphasis is on target volume delineation for three-dimensional conformal therapy and IMRT, information is also provided on conventional radiation therapy field setup and planning for certain malignancies for which IMRT is not currently suitable.
Conformal use of retarded Green's functions for the Maxwell field in de Sitter space
International Nuclear Information System (INIS)
Faci, S.; Huguet, E.; Renaud, J.
2011-01-01
We propose a new propagation formula for the Maxwell field in de Sitter space which exploits the conformal invariance of this field together with a conformal gauge condition. This formula allows to determine the classical electromagnetic field in the de Sitter space from given currents and initial data. It only uses the Green's function of the massless Minkowskian scalar field. This leads to drastic simplifications in practical calculations. We apply this formula to the classical problem of the two charges of opposite signs at rest at the North and South Poles of the de Sitter space.
Revisiting the conformal invariance of the scalar field: From Minkowski space to de Sitter space
International Nuclear Information System (INIS)
Huguet, E.; Queva, J.; Renaud, J.
2008-01-01
In this article, we clarify the link between the conformal (i.e. Weyl) correspondence from the Minkowski space to the de Sitter space and the conformal [i.e. SO(2,d)] invariance of the conformal scalar field on both spaces. We exhibit the realization on de Sitter space of the massless scalar representation of SO(2,d). It is obtained from the corresponding representation in Minkowski space through an intertwining operator inherited from the Weyl relation between the two spaces. The de Sitter representation is written in a form which allows one to take the point of view of a Minkowskian observer who sees the effect of curvature through additional terms
International Nuclear Information System (INIS)
Oono, Y.; Ohta, T.; Freed, K.F.
1981-01-01
A dimensional regularization approach to the renormalization group treatment of polymer excluded volume is formulated in chain conformation space where monomers are specified by their spatial positions and their positions along the chain and the polymers may be taken to be monodisperse. The method utilizes basic scale invariance considerations. First, it is recognized that long wavelength macroscopic descriptions must be well defined in the limit that the minimum atomic or molecular scale L is set to zero. Secondly, the microscopic theory is independent of the conveniently chosen macroscopic scale of length k. The freedom of choice of k is exploited along with the assumed renormalizability of the theory to provide the renormalization group equations which directly imply the universal scaling laws for macroscopic properties. The renormalizability of the model implies the existence of the general relations between the basic macroparameters, such as chain length, excluded volume, etc., and their microscopic counterparts in the microscopic model for the system. These macro--micro relations are defined through the condition that macroscopic quantities be well defined for polymer chains for any spatial dimensionality. The method is illustrated by calculating the end vector distribution function for all values of end vectors R. The evaluation of this distribution function currently requires the use of expansions in e = 4-d. In this case our distribution reduces to known limits for R→0 or infinity. Subsequent papers will present calculations of the polymer coherent scattering function, the monomer spatial distribution function, and concentration dependent properties
Directory of Open Access Journals (Sweden)
Seied R Mahdavi
2012-01-01
Full Text Available Aims: The objective of this study is to evaluate the accuracy of a treatment planning system (TPS for calculating the dose distribution parameters in conformal fields (CF. Dosimetric parameters of CF′s were compared between measurement, Monte Carlo simulation (MCNP4C and TPS calculation. Materials and Methods: Field analyzer water phantom was used for obtaining percentage depth dose (PDD curves and beam profiles (BP of different conformal fields. MCNP4C was used to model conformal fields dose specification factors and head of linear accelerator varian model 2100C/D. Results: Results showed that the distance to agreement (DTA and dose difference (DD of our findings were well within the acceptance criteria of 3 mm and 3%, respectively. Conclusions: According to this study it can be revealed that TPS using equivalent tissue air ratio calculation method is still convenient for dose prediction in non small conformal fields normally used in prostate radiotherapy. It was also showed that, since there is a close correlation with Monte Carlo simulation, measurements and TPS, Monte Carlo can be further confirmed for implementation and calculation dose distribution in non standard and complex conformal irradiation field for treatment planning systems.
Conformal scalar fields and chiral splitting on super Riemann surfaces
International Nuclear Information System (INIS)
D'Hoker, E.; Phong, D.H.
1989-01-01
We provide a complete description of correlation functions of scalar superfields on a super Riemann surface, taking into account zero modes and non-trivial topology. They are built out of chirally split correlation functions, or conformal blocks at fixed internal momenta. We formulate effective rules which determine these completely in terms of geometric invariants of the super Riemann surface. The chirally split correlation functions have non-trivial monodromy and produce single-valued amplitudes only upon integration over loop momenta. Our discussion covers the even spin structure as well as the odd spin structure case which had been the source of many difficulties in the past. Super analogues of Green's functions, holomorphic spinors, and prime forms emerge which should pave the way to function theory on super Riemann surfaces. In superstring theories, chirally split amplitudes for scalar superfields are crucial in enforcing the GSO projection required for consistency. However one really knew how to carry this out only in the operator formalism to one-loop order. Our results provide a way of enforcing the GSO projection to any loop. (orig.)
Modular invariance and (quasi)-Galois symmetry in conformal field theory
International Nuclear Information System (INIS)
Schellekens, A.N.
1995-01-01
A brief heuristic explanation is given of recent work with Juergen Fuchs, Beatriz Gato-Rivera and Christoph Schweigert on the construction of modular invariant partition functions from Galois symmetry in conformal field theory. A generalization, which we call quasi-Galois symmetry, is also described. As an application of the latter, the invariants of the exceptional algebras at level g (for example E s level 30) expected from conformal embeddings are presented. (orig.)
Properties of partial-wave amplitudes in conformal invariant field theories
Ferrara, Sergio; Grillo, A F
1975-01-01
Analyticity properties of partial-wave amplitudes of the conformal group O/sub D,2/ (D not necessarily integer) in configuration space are investigated. The presence of Euclidean singularities in the Wilson expansion in conformal invariant field theories is discussed, especially in connection with the program of formulating dynamical bootstrap conditions coming from the requirement of causality. The exceptional case of D-2 is discussed in detail. (18 refs).
International Nuclear Information System (INIS)
Feuvret, Loic; Noel, Georges; Mazeron, Jean-Jacques; Bey, Pierre
2006-01-01
We present a critical analysis of the conformity indices described in the literature and an evaluation of their field of application. Three-dimensional conformal radiotherapy, with or without intensity modulation, is based on medical imaging techniques, three-dimensional dosimetry software, compression accessories, and verification procedures. It consists of delineating target volumes and critical healthy tissues to select the best combination of beams. This approach allows better adaptation of the isodose to the tumor volume, while limiting irradiation of healthy tissues. Tools must be developed to evaluate the quality of proposed treatment plans. Dosimetry software provides the dose distribution in each CT section and dose-volume histograms without really indicating the degree of conformity. The conformity index is a complementary tool that attributes a score to a treatment plan or that can compare several treatment plans for the same patient. The future of conformal index in everyday practice therefore remains unclear
Backreaction from non-conformal quantum fields in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Perez-Nadal, Guillem; Verdaguer, Enric [Departament de Fisica Fonamental and Institut de Ciencies del Cosmos, Universitat de Barcelona, Av Diagonal 647, 08028 Barcelona (Spain); Roura, Albert [Theoretical Division, T-8, Los Alamos National Laboratory, M.S. B285, Los Alamos, NM 87545 (United States)
2008-08-07
We study the backreaction on the mean field geometry due to a non-conformal quantum field in a Robertson-Walker background. In the regime of small mass and small deviation from conformal coupling, we compute perturbatively the expectation value of the stress tensor of the field for a variety of vacuum states, and use it to obtain explicitly the semiclassical gravity solutions for isotropic perturbations around de Sitter spacetime, which is found to be stable. Our results clearly show the crucial role of the non-local terms that appear in the effective action: they cancel the contribution from local terms proportional to the logarithm of the scale factor which would otherwise become dominant at late times and prevent the existence of a stable self-consistent de Sitter solution. Finally, the opposite regime of a strongly non-conformal field with a large mass is also considered.
Exploring conformational space using a mean field technique with ...
Indian Academy of Sciences (India)
PRAKASH KUMAR
2007-06-21
Jun 21, 2007 ... structure of a peptide or protein have their fundamental theoretical ..... MOLS procedure has not considered such intermolecular interactions. ..... Takada S 2001 Protein Folding Simulation With Solvent-Induced. Force Field: ...
Energy Technology Data Exchange (ETDEWEB)
Trouette, R; Causse, N; Elkhadri, M; Caudry, M; Maire, J P; Houlard, J P; Racaldini, L; Demeaux, H
1995-12-01
Three dimensional conformal radiation therapy would allow to decrease the normal tissue dose while maintaining the same target dose as standard treatment. To evaluate the feasibility of normal tissue dose reduction for ten patients with pneumonectomy for lung cancer, we determined the dose distribution to the normal tissue with 3-dimensional conformal radiation therapy (3-DCRT) and conventional treatment planning (CTP). Dose-volume histograms for target and normal tissue (lung, heart) were used for comparison of the different treatment planning. The mean percentages of lung and heart volumes which received 40 Gy with 3-DCRT were respectively 63% and 37% of the mean percentage of lung and volumes which received the same dose with CTP. These preliminary results suggest that conformal therapy may improve the therapeutic ratio by reducing risk to normal tissue.
On the existence of pointlike localized fields in conformally invariant quantum physics
International Nuclear Information System (INIS)
Joerss, M.
1992-11-01
In quantum field theory the existence of pointlike localizable objects called 'fields' is a preassumption. Since charged fields are in general not observable this situation is unsatisfying from a quantum physics point of view. Indeed in any quantum theory the existence of fields should follow from deeper physical concepts and more natural first principles like stability, locality, causality and symmetry. In the framework of algebraic quantum field theory with Haag-Kastler nets of local observables this is presented for the case of conformal symmetry in 1+1 dimensions. Conformal fields are explicitly constructed as limits of observables localized in finite regions of space-time. These fields then allow to derive a geometric identification of modular operators, Haag duality in the vacuum sector, the PCT-theorem and an equivalence theorem for fields and algebras. (orig.)
van der Laan, Hans Paul; Dolsma, Willemtje; van t Veld, Aart; Bijl, HP; Langendijk, JA
2005-01-01
PURPOSE: To compare the Para Mixed technique for irradiation of the internal mammary nodes (IMN) with three commonly used strategies, by analyzing the dose to the heart and other organs at risk. METHODS AND MATERIALS: Four different three-dimensional conformal dose plans were created for 30 breast
International Nuclear Information System (INIS)
Wu Li; Wen Xiaoping; Huang Wei
2006-01-01
Objective: To evaluate the effects of three-dimensional conformal radiation therapy (3DCRT) combined with transcatheter arterial chemoembolization (TACE) on stage m/IV primary hepatic carcinoma. Methods: Eighty cases of stage III/IV primary hepatic carcinoma were randomly divided into two groups: 40 cases treated with three-dimensional conformal radiation therapy combined with transcatheter arterial chemoembolization (3DCRT + TACE group) and 40 cases treated with three-dimensional conformal radiation therapy associated with hepatic arterial infusion chemotherapy (3DCRT +HAI group). Results: The response rates were 75% and 45% in 3DCRT + TACE group and 3DCRT + HAI group, respectively; and the difference between the two groups was statistically significant (P 0.05), The 0.5-, 1- and 2-year survival rates were 73% , 45% and 28% in 3DCRT + TACE group, and 45%, 25% and 13% in 3DCRT + HAI group, respectively; and the difference between the two groups was statistically significant (P 0.05). Conclusion: Three-dimensional conformal radiation therapy combined with transcatheter arterial chemoembolization improved prognosis of stage III/IV primary hepatic carcinoma. (authors)
Thermalization and revivals after a quantum quench in conformal field theory.
Cardy, John
2014-06-06
We consider a quantum quench in a finite system of length L described by a 1+1-dimensional conformal field theory (CFT), of central charge c, from a state with finite energy density corresponding to an inverse temperature β≪L. For times t such that ℓ/2
Bianchi type-I model with conformally invariant scalar and electromagnetic field
International Nuclear Information System (INIS)
Accioly, A.J.; Vaidya, A.N.; Som, M.M.
1983-01-01
A Bianchi type-I exact solution of the Einstein theory representing the homogeneous anisotropic models with the electromagnetic field and the conformally invariant scalar field is studied. The solution contains Kasner model, pure electromagnetic and pure scalar models as special cases. It is found that the models evolve from an initial Kasner type to a final open Friedmann type universe. (Author) [pt
Energy Technology Data Exchange (ETDEWEB)
Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Owen, Steven J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Abdeljawad, Fadi F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hanks, Byron [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-09-01
In order to better incorporate microstructures in continuum scale models, we use a novel finite element (FE) meshing technique to generate three-dimensional polycrystalline aggregates from a phase field grain growth model of grain microstructures. The proposed meshing technique creates hexahedral FE meshes that capture smooth interfaces between adjacent grains. Three dimensional realizations of grain microstructures from the phase field model are used in crystal plasticity-finite element (CP-FE) simulations of polycrystalline a -iron. We show that the interface conformal meshes significantly reduce artificial stress localizations in voxelated meshes that exhibit the so-called "wedding cake" interfaces. This framework provides a direct link between two mesoscale models - phase field and crystal plasticity - and for the first time allows mechanics simulations of polycrystalline materials using three-dimensional hexahedral finite element meshes with realistic topological features.
Study of one dimensional magnetic system via field theory
International Nuclear Information System (INIS)
Talim, S.L.
1988-04-01
We present a study of one-dimensional magnetic system using field theory methods. We studied the discreteness effects in a classical anisotropic one dimensional antiferromagnet in an external magnetic field. It is shown that for TMMC, at the temperatures and magnetic fields where most experiments have been done, the corrections are small and can be neglected. (author)
International Nuclear Information System (INIS)
Zheng Xiaokang; Ma Jun; Chen Longhua; Xia Yunfei; Shi Yusheng
2005-01-01
Purpose: To assess the dosimetric and clinical results of three-dimensional conformal radiotherapy (3D CRT) for locally recurrent nasopharyngeal carcinoma (NPC). Methods: A total of 86 patients with locally recurrent NPC were retreated with 3D CRT. The median prescribed dose was 68 Gy with 2 Gy per fractionation. Dosimetric quality was evaluated with dose distribution in planning target volume (PTV) and specified organs at risk (OAR), dose conformity index (CI) and dose homogeneity index (HI). The actuarial rate of local failure-free (LFF), overall survival (OS) and major late toxicities (MLT) were estimated with Kaplan-Meier method. Multivariate analysis for prognosis was performed using the Cox regression proportional hazards model. Results: The mean dose to PTV averaged 66.8 Gy, and the dose to specified OAR was acceptable. The average value of CI and HI was 0.59 and 9.1%. The 5-year actuarial rate of LFF and OS was 71 and 40%, respectively. The 5-year actuarial incidence of MLT≥Grade 3 and ≥Grade 4 were 100 and 49%, respectively. The major prognostic factors were T stage and the size of gross tumor volume (GTV). Advanced T stage and large GTV volume were associated with poor LFF and OS and high risk of MLT. Conclusion: The dosimetric quality of 3D CRT for locally recurrent NPC is generally excellent. A relatively high local control was achieved with this technique. However, the incidence of late toxicities were not found to decrease as originally expected. Early diagnosis of the recurrence and reasonable definition of the target volume are crucial to achieve a better outcome
Galois and simple current symmetries in conformal field theory
International Nuclear Information System (INIS)
Schweigert, C.
1995-01-01
In this thesis various aspects of rational field theories are studied. In part I explicit examples for N=2 superconformal field theories are constructed by means of the coset approach. By means of these models string vacua are constructed, and the massless spectra of the string compactifications based on these models are computed. The symmetry of the S matrix, which implements the modular transformation on the space of characters is the subject of Part II. The developed methods are applied to the fusion rings of WZW theories. (HSI)
The gluonic field of a heavy quark in conformal field theories at strong coupling
Chernicoff, Mariano; Güijosa, Alberto; Pedraza, Juan F.
2011-10-01
We determine the gluonic field configuration sourced by a heavy quark undergoing arbitrary motion in mathcal{N} = 4 super-Yang-Mills at strong coupling and large number of colors. More specifically, we compute the expectation value of the operator Tr[ F 2 + …] in the presence of such a quark, by means of the AdS/CFT correspondence. Our results for this observable show that signals propagate without temporal broadening, just as was found for the expectation value of the energy density in recent work by Hatta et al. We attempt to shed some additional light on the origin of this feature, and propose a different interpretation for its physical significance. As an application of our general results, we examine (Tr[ F 2 + …])when the quark undergoes oscillatory motion, uniform circular motion, and uniform acceleration. Via the AdS/CFT correspondence, all of our results are pertinent to any conformal field theory in 3 + 1 dimensions with a dual gravity formulation.
International Nuclear Information System (INIS)
Soyfer, Viacheslav; Corn, Benjamin W.; Melamud, Alex B.S.; Alani, Shlomi; Tempelhof, Haim; Agai, Reuben; Shmueli, Anat; Figer, Arie; Kovner, Felix
2007-01-01
Purpose: The current standard of adjuvant treatment for gastric cancer after curative resection is concurrent administration of radiotherapy and 5-fluorouracil-based chemotherapy. The radiation fields are often arranged as anterioposterior-posteroanterior opposed parallel fields with general recommendations for sparing at least two-thirds of one kidney. We investigated whether a better radiation distribution would be achievable with three-dimensional conformal approaches compared with the classic anterioposterior-posteroanterior fields. Methods and Materials: A total of 19 patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a non-coplanar four-field arrangement. In each case, parallel planning using an anterioposterior-posteroanterior arrangement and a four-field 'box' was performed, and the generated plans were subsequently compared for coverage of target volumes and doses to irradiated organs next to the tumor bed. A separate analysis was performed for kidneys exposed to greater and lower doses in each patient. The mean radiation dose and percentage of kidney volume receiving a dose >20 Gy were registered. Statistical analysis was performed using the two-tailed t test. Results: The clinical target volume was adequately covered in all three plans. In the greater-dose kidney group, all the differences were statistically significant with a benefit for the three-dimensional plan. In the lower-dose kidney group, the differences in the mean radiation dose did not reach the level of statistical significance, and the differences in the kidney volume receiving a dose >20 Gy showed a statistically significant benefit for the three-dimensional plan. Conclusion: Non-coplanar three-dimensional-based conformal planning for postoperative radiotherapy for gastric cancer provided the best results regarding kidney and spinal cord exposure with adequate clinical target volume coverage. This technique was readily implemented in clinical
Soyfer, Viacheslav; Corn, Benjamin W; Melamud, Alex; Alani, Shlomi; Tempelhof, Haim; Agai, Reuben; Shmueli, Anat; Figer, Arie; Kovner, Felix
2007-10-01
The current standard of adjuvant treatment for gastric cancer after curative resection is concurrent administration of radiotherapy and 5-fluorouracil-based chemotherapy. The radiation fields are often arranged as anterioposterior-posteroanterior opposed parallel fields with general recommendations for sparing at least two-thirds of one kidney. We investigated whether a better radiation distribution would be achievable with three-dimensional conformal approaches compared with the classic anterioposterior-posteroanterior fields. A total of 19 patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a non-coplanar four-field arrangement. In each case, parallel planning using an anterioposterior-posteroanterior arrangement and a four-field "box" was performed, and the generated plans were subsequently compared for coverage of target volumes and doses to irradiated organs next to the tumor bed. A separate analysis was performed for kidneys exposed to greater and lower doses in each patient. The mean radiation dose and percentage of kidney volume receiving a dose >20 Gy were registered. Statistical analysis was performed using the two-tailed t test. The clinical target volume was adequately covered in all three plans. In the greater-dose kidney group, all the differences were statistically significant with a benefit for the three-dimensional plan. In the lower-dose kidney group, the differences in the mean radiation dose did not reach the level of statistical significance, and the differences in the kidney volume receiving a dose >20 Gy showed a statistically significant benefit for the three-dimensional plan. Non-coplanar three-dimensional-based conformal planning for postoperative radiotherapy for gastric cancer provided the best results regarding kidney and spinal cord exposure with adequate clinical target volume coverage. This technique was readily implemented in clinical practice.
Chiral gauged Wess-Zumino-Witten theories and coset models in conformal field theory
International Nuclear Information System (INIS)
Chung, S.; Tye, S.H.
1993-01-01
The Wess-Zumino-Witten (WZW) theory has a global symmetry denoted by G L direct-product G R . In the standard gauged WZW theory, vector gauge fields (i.e., with vector gauge couplings) are in the adjoint representation of the subgroup H contained-in G. In this paper, we show that, in the conformal limit in two dimensions, there is a gauged WZW theory where the gauge fields are chiral and belong to the subgroups H L and H R where H L and H R can be different groups. In the special case where H L =H R , the theory is equivalent to vector gauged WZW theory. For general groups H L and H R , an examination of the correlation functions (or more precisely, conformal blocks) shows that the chiral gauged WZW theory is equivalent to (G/H L ) L direct-product(G/H R ) R coset models in conformal field theory
International Nuclear Information System (INIS)
Skala, M.; Berry, M.; Kneebone, A.; Gogna, K.; Turner, S.; Rolfo, A.; Haworth, A.
2004-01-01
Three-dimensional conformal radiation therapy (3DCRT) has been shown to reduce normal tissue toxicity and allow dose escalation in the curative treatment of prostate cancer. The Faculty of Radiation Oncology Genito-Urinary Group initiated a consensus process to generate evidence-based guidelines for the safe and effective implementation of 3DCRT. All radiation oncology departments in Australia and New Zealand were invited to complete a survey of their prostate practice and to send representatives to a consensus workshop. After a review of the evidence, key issues were identified and debated. If agreement was not reached, working parties were formed to make recommendations. Draft guidelines were circulated to workshop participants for approval prior to publication. Where possible, evidence-based recommendations have been made with regard to patient selection, risk stratification, simulation, planning, treatment delivery and toxicity reporting. This is the first time a group of radiation therapists, physicists and oncologists representing professional radiotherapy practice across Australia and New Zealand have worked together to develop best-practice guidelines. These guidelines should serve as a baseline for prospective clinical trials, outcome research and quality assurance. Copyright (2004) Blackwell Science Pty Ltd
International Nuclear Information System (INIS)
Giraud, P.; Jaulerry, C.; Brunin, F.; Zefkili, S.; Helfre, S.; Chauvet, I.; Rosenwald, J.C.; Cosset, J.M.
2002-01-01
The conformal radiotherapy approach, three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT), is based on modern imaging modalities, efficient 3-D treatment planning systems, sophisticated immobilization systems and rigorous quality assurance and treatment verification. The central objective of conformal radiotherapy is to ensure a high dose distribution tailored to the limits of the target volume while reducing exposure of normal tissues. These techniques would then allow further tumor dose escalation. Head-and-neck tumors are some of the most attractive localizations to test conformal radiotherapy. They combine ballistic difficulties due to particularly complex shapes (nasopharynx, ethmoid) and problems due to the number and low tolerance of neighbouring organs like parotids, eyes, brainstem and spinal cord. The therapeutic irradiation of head-and-neck tumors thus remains a challenge for the radiation oncologist. Conformal radiotherapy does have a significant potential for improving local control and reducing toxicity when compared to standard radiotherapy. However, in the absence of prospective randomized trials, it is somewhat difficult at present to evaluate the real benefits drawn from 3DCRT and IMRT. The published clinical reports on the use of conformal radiotherapy are essentially dealing with dosimetric comparisons on relatively small numbers of patients. Recently, a few publications have emphasized the clinical experience several precursor teams with a suitable follow-up. This paper describes the current state-of-the-art of 3DCRT and IMRT in order to evaluate the impact of these techniques on head-and-neck cancers irradiation. (authors)
Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham
2013-01-01
Introduction Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. Methods A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. Results The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. Conclusion The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques. PMID:26229623
International Nuclear Information System (INIS)
Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham
2013-01-01
Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques
Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham
2013-12-01
Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147-53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose-volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.
Energy Technology Data Exchange (ETDEWEB)
Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham [Andrew Love Cancer Centre, Geelong Hospital, Geelong, Victoria (Australia)
2013-12-15
Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.
International Nuclear Information System (INIS)
Lennernaes, B.; Rikner, G.; Letocha, H.; Nilsson, S.
1995-01-01
The purpose of the present study was to identify factors of importance in the planning of external beam radiotherapy of prostatic adenocarcinoma. Seven patients with urogenital cancers were planned for external radiotherapy of the prostate. Four different techniques were used, viz. a 4-field box technique and four-, five- or six-field conformal therapy set-ups combined with three different margins (1-3 cm). The evaluations were based on the doses delivered to the rectum and the urinary bladder. A normal tissue complication probability (NTCP) was calculated for each plan using Lyman's dose volume reduction method. The most important factors that resulted in a decrease of the dose delivered to the rectum and the bladder were the use of conformal therapy and smaller margins. Conformal therapy seemed more important for the dose distribution in the urinary bladder. Five- and six-field set-ups were not significantly better than those with four fields. NTCP calculations were in accordance with the evaluation of the dose volume histograms. To conclude, four-field conformal therapy utilizing reduced margins improves the dose distribution to the rectum and the urinary bladder in the radiotherapy of prostatic adenocarcinoma. (orig.)
Space- and time-like superselection rules in conformal quantum field theory
International Nuclear Information System (INIS)
Schroer, Bert
2000-11-01
In conformally invariant quantum field theories one encounters besides the standard DHR superselection theory based on spacelike (Einstein-causal) commutation relations and their Haag duality another timelike (Huygens) based superselection structure. Whereas the DHR theory based on spacelike causality of observables confirmed the Lagrangian internal symmetry picture on the level of the physical principles of local quantum physics, the attempts to understand the timelike based superselection charges associated with the center of the conformal covering group in terms of timelike localized charges lead to a more dynamical role of charges outside the DR theorem and even outside the Coleman-Mandula setting. The ensuing plektonic timelike structure of conformal theories explains the spectrum of the anomalous scale dimensions in terms of admissible braid group representations, similar to the explanation of the possible anomalous spin spectrum expected from the extension of the DHR theory to stringlike d=1+2 plektonic fields. (author)
Automorphisms of W-algebras and extended rational conformal field theories
International Nuclear Information System (INIS)
Honecker, A.
1992-11-01
Many extended conformal algebras with one generator in addition to the Virasoro field as well as Casimir algebras have non-trivial outer automorphisms which enables one to impose 'twisted' boundary conditions on the chiral fields. We study their effect on the highest weight representations. We give formulae for the enlarged rational conformal field theories in both series of W-algebras with two generators and conjecture a general formula for the additional models in the minimal series of Casimir algebras. A third series of W-algebras with two generators which includes the spin three algebra at c = -2 also has finitely many additional fields in the twisted sector although the model itself is apparently not rational. The additional fields in the twisted sector have applications in statistical mechanics as we demonstrate for Z n -quantum spin chains with a particular type of boundary conditions. (orig.)
Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields
Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes
2014-01-01
Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.
Quantum field between moving mirrors: A three dimensional example
Hacyan, S.; Jauregui, Roco; Villarreal, Carlos
1995-01-01
The scalar quantum field uniformly moving plates in three dimensional space is studied. Field equations for Dirichlet boundary conditions are solved exactly. Comparison of the resulting wavefunctions with their instantaneous static counterpart is performed via Bogolubov coefficients. Unlike the one dimensional problem, 'particle' creation as well as squeezing may occur. The time dependent Casimir energy is also evaluated.
International Nuclear Information System (INIS)
Cai Yong; He Yuxiang; Han Shukui; Wu Hao; Gong Jian; Xu Bo
2007-01-01
Objective: To compare the dose distribution of clinical target volume (CTV), in normal tissues and organs for patients with rectal cancer on the conventional radiotherapy (2D) and three dimension- al conformal radiation treatment (3DCRT). Methods: The CT image data of 36 rectal cancer patients treated with 3DCRT were studied. The CTV, small bowel, colon, bladder, pelvic bone marrow, and femoral head and neck were contoured on consecutive axial slices of CT images. Two 3DCRT and three conventional treatment planning protocols were simulated using three dimensional treatment planning system (CMS Focus 2.31), were defined as 3D-3, 3D-4, 2D-2, 2D-3, 2D-4. The difference of five treatment planning protocols on the CTV and normal structure by analysis of dose-volume histograms (DVHs) were compared. Results: The D 95 and V 95 of these five protocols all exceeded 97%. The conformity index(CI) of 3D was obviously larger than that of 2D protocol. The dose inhomogeneity(DI) in 4 DCRT was less than that of 3 DCRT. The 3D as compared with the 2D, significantly reduced the mean dose of 45 Gy to the small bowel and colon. The 3D-3 as compared with the 2D-3, the 3D-4 as compared with the 2D-4, the mean dose of small bowel and colon was reduced by 28.5% and 25.7%, respectively. The 3D-3 as compared with the 2D-2, the 3D-3 as compared with the 2D-3 and the 3D4 as compared with the 2D-4, the percentage volume of small bowel and colon which received 45 Gy was reduced by 80.8% , 51.1% and 54.7% , respectively. Either the mean dose, or the percentage volume receiving 35 Gy and 45 Gy to the pelvic bone and bladder, the 3D planning protocols had advanage over the 2D planning protocols. The V 45 of bladder in 2D-2 planning proto- col was the highest in all planning protocols, exceeding 98%, but the highest V 45 of bladder was only 50% in the other planning protocols. Conclusions: Even though the difference in pelvic CTV of rectal cancer patients between the conventional radiotherapy and 3
Conformally invariant amplitudes and field theory in a space-time of constant curvature
International Nuclear Information System (INIS)
Drummond, I.T.
1977-02-01
The problem of calculating the ultra violet divergences of a field theory in a spherical space-time is reduced to analysing the pole structure of conformally invariant integrals which are analogous to amplitudes which occur in the theory of dual models. The calculations are illustrated with phi 3 -theory in six-dimensions. (author)
Conformally invariant amplitudes and field theory in a spacetime of constant curvature
International Nuclear Information System (INIS)
Drummond, I.T.
1979-01-01
The problem of calculating the ultraviolet divergences of a field theory in a spherical spacetime is reduced to analyzing the pole structure of conformally invariant integrals which are analogous to amplitudes which occur in the theory of dual models. The calculations are illustrated with phi 3 theory in six dimensions
An introduction to conformal invariance in quantum field theory and statistical mechanics
International Nuclear Information System (INIS)
Boyanovsky, D.; Naon, C.M.
1990-01-01
The subject of conformal invariance provides an extraordinarly successful and productive symbiosis between statistical mechanics and quantum field theory. The main goal of this paper, which is tailored to a wide audience, is to give an introduction to such vast subject (C.P.)
Extended KN algebras and extended conformal field theories over higher genus Riemann surfaces
International Nuclear Information System (INIS)
Ceresole, A.; Huang Chaoshang
1990-01-01
A global operator formalism for extended conformal field theories over higher genus Riemann surfaces is introduced and extended KN algebra are obtained by means of the KN bases. The BBSS construction of the spin-3 operator is carried out for Kac-Moody algebra A 2 over a Riemann surface of arbitrary genus. (orig.)
Informal introduction to extended algebras and conformal field theories with c ≥ 1
International Nuclear Information System (INIS)
Ravanini, F.
1989-01-01
We review some of the topics of Conformal Field Theory, like extended algebras, parafermions, coset constructions and generalized Feigin-Fuchs construction, modular invariant partition functions on the torus and the help they give in classification of CFTs. Some recent issues in RCFT are also discussed. (orig.)
International Nuclear Information System (INIS)
Yu, Mina; Lee, Hyo Chun; Chung, Mi Joo; Kim, Sung Hwan; Lee, Jong Hoon; Jang, Hong Seok; Jeon, Dong Min; Cheon, Geum Seong
2013-01-01
To report the results of dosimetric comparison between intensity-modulated radiotherapy (IMRT) using Tomotherapy and four-box field conformal radiotherapy (CRT) for pelvic irradiation of locally advanced rectal cancer. Twelve patients with locally advanced rectal cancer who received a short course preoperative chemoradiotherapy (25 Gy in 5 fractions) on the pelvis using Tomotherapy, between July 2010 and December 2010, were selected. Using their simulation computed tomography scans, Tomotherapy and four-box field CRT plans with the same dose schedule were evaluated, and dosimetric parameters of the two plans were compared. For the comparison of target coverage, we analyzed the mean dose, Vn Gy, Dmin, Dmax, radical dose homogeneity index (rDHI), and radiation conformity index (RCI). For the comparison of organs at risk (OAR), we analyzed the mean dose. Tomotherapy showed a significantly higher mean target dose than four-box field CRT (p 0.001). But, V26.25 Gy and V27.5 Gywere not significantly different between the two modalities. Tomotherapy showed higher Dmax and lower Dmin. The Tomotherapy plan had a lower rDHI than four-box field CRT (p = 0.000). Tomotherapy showed better RCI than four-box field CRT (p = 0.007). For OAR, the mean irradiated dose was significantly lower in Tomotherapy than four-box field CRT. In locally advanced rectal cancer, Tomotherapy delivers a higher conformal radiation dose to the target and reduces the irradiated dose to OAR than four-box field CRT.
Energy Technology Data Exchange (ETDEWEB)
Yu, Mina; Lee, Hyo Chun; Chung, Mi Joo; Kim, Sung Hwan; Lee, Jong Hoon [Dept. of Radiation Oncology, St. Vincent' s Hospital, The Catholic University of Korea College of Medicine, Suwon (Korea, Republic of); Jang, Hong Seok; Jeon, Dong Min; Cheon, Geum Seong [Dept. of Radiation Oncology, Seoul St. Mary' s Hospital, The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of)
2013-12-15
To report the results of dosimetric comparison between intensity-modulated radiotherapy (IMRT) using Tomotherapy and four-box field conformal radiotherapy (CRT) for pelvic irradiation of locally advanced rectal cancer. Twelve patients with locally advanced rectal cancer who received a short course preoperative chemoradiotherapy (25 Gy in 5 fractions) on the pelvis using Tomotherapy, between July 2010 and December 2010, were selected. Using their simulation computed tomography scans, Tomotherapy and four-box field CRT plans with the same dose schedule were evaluated, and dosimetric parameters of the two plans were compared. For the comparison of target coverage, we analyzed the mean dose, Vn Gy, Dmin, Dmax, radical dose homogeneity index (rDHI), and radiation conformity index (RCI). For the comparison of organs at risk (OAR), we analyzed the mean dose. Tomotherapy showed a significantly higher mean target dose than four-box field CRT (p 0.001). But, V26.25 Gy and V27.5 Gywere not significantly different between the two modalities. Tomotherapy showed higher Dmax and lower Dmin. The Tomotherapy plan had a lower rDHI than four-box field CRT (p = 0.000). Tomotherapy showed better RCI than four-box field CRT (p = 0.007). For OAR, the mean irradiated dose was significantly lower in Tomotherapy than four-box field CRT. In locally advanced rectal cancer, Tomotherapy delivers a higher conformal radiation dose to the target and reduces the irradiated dose to OAR than four-box field CRT.
K theoretical approach to the fusion rules of conformal quantum field theories
International Nuclear Information System (INIS)
Recknagel, A.
1993-09-01
Conformally invariant quantum field theories are investigated using concepts of the algebraic approach to quantum field theory as well as techniques from the theory of operator algebras. Arguments from the study of statistical lattice models in one and two dimensions, from recent developments in algebraic quantum field theory, and from other sources suggest that there exists and intimate connection between conformal field theories and a special class of C*-algebras, the so-called AF-algebras. For a series of Virasoro minimal models, this correspondence is made explicit by constructing path representations of the irreducible highest weight modules. We then focus on the K 0 -invariant of these path AF-algebras and show how its functorial properties allow to exploit the abstract theory of superselection sectors in order to derive the fusion rules of the W-algebras hidden in the Virasoro minimal models. (orig.)
International Nuclear Information System (INIS)
Laan, Hans Paul van der; Dolsma, Wil V.; Maduro, John H.; Korevaar, Erik W.; Hollander, Miranda; Langendijk, Johannes A.
2007-01-01
Purpose: To compare the target coverage and normal tissue dose with the simultaneously integrated boost (SIB) and the sequential boost technique in breast cancer, and to evaluate the incidence of acute skin toxicity in patients treated with the SIB technique. Methods and Materials: Thirty patients with early-stage left-sided breast cancer underwent breast-conserving radiotherapy using the SIB technique. The breast and boost planning target volumes (PTVs) were treated simultaneously (i.e., for each fraction, the breast and boost PTVs received 1.81 Gy and 2.3 Gy, respectively). Three-dimensional conformal beams with wedges were shaped and weighted using forward planning. Dose-volume histograms of the PTVs and organs at risk with the SIB technique, 28 x (1.81 + 0.49 Gy), were compared with those for the sequential boost technique, 25 x 2 Gy + 8 x 2 Gy. Acute skin toxicity was evaluated for 90 patients treated with the SIB technique according to Common Terminology Criteria for Adverse Events, version 3.0. Results: PTV coverage was adequate with both techniques. With SIB, more efficiently shaped boost beams resulted in smaller irradiated volumes. The mean volume receiving ≥107% of the breast dose was reduced by 20%, the mean volume outside the boost PTV receiving ≥95% of the boost dose was reduced by 54%, and the mean heart and lung dose were reduced by 10%. Of the evaluated patients, 32.2% had Grade 2 or worse toxicity. Conclusion: The SIB technique is proposed for standard use in breast-conserving radiotherapy because of its dose-limiting capabilities, easy implementation, reduced number of treatment fractions, and relatively low incidence of acute skin toxicity
International Nuclear Information System (INIS)
Valicenti, Richard K.; Sweet, John W.; Hauck, Walter W.; Hudes, Richard S.; Lee, Tony; Dicker, Adam P.; Waterman, Frank M.; Anne, Pramila R.; Corn, Benjamin W.; Galvin, James M.
1999-01-01
Purpose: Currently, three-dimensional conformal radiation therapy (3D-CRT) planning relies on the interpretation of computed tomography (CT) axial images for defining the clinical target volume (CTV). This study investigates the variation among multiple observers to define the CTV used in 3D-CRT for prostate cancer. Methods and Materials: Seven observers independently delineated the CTVs (prostate ± seminal vesicles [SV]) from the CT simulation data of 10 prostate cancer patients undergoing 3D-CRT. Six patients underwent CT simulation without the use of contrast material and serve as a control group. The other 4 had urethral and bladder opacification with contrast medium. To determine interobserver variation, we evaluated the derived volume, the maximum dimensions, and the isocenter for each examination of CTV. We assessed the reliability in the CTVs among the observers by correlating the variation for each class of measurements. This was estimated by intraclass correlation coefficient (ICC), with 1.00 defining absolute correlation. Results: For the prostate volumes, the ICC was 0.80 (95% confidence interval [CI]: 0.56-0.96). This changed to 0.92 (95% CI: 0.75-0.99) with the use of contrast material. Similarly, the maximal prostatic dimensions were reliable and improved. There was poor agreement in defining the SV. For this structure, the ICC never exceeded 0.28. The reliability of the isocenter was excellent, with the ICC exceeding 0.83 and 0.90 for the prostate ± SV, respectively. Conclusions: In 3D-CRT for prostate cancer, there was excellent agreement among multiple observers to define the prostate target volume but poor agreement to define the SV. The use of urethral and bladder contrast improved the reliability of localizing the prostate. For all CTVs, the isocenter was very reliable and should be used to compare the variation in 3D dosimetry among multiple observers
Hypofractionated three-dimensional conformal radiotherapy for medically inoperable early stage
Energy Technology Data Exchange (ETDEWEB)
Lee, Joo Ho; Wu, Hong Gyun; KIm, Hak Jae; Park, Charn Il; Lee, Se Hoon; Kim, Dong Wan; Heo, Dae Seong [Seoul National University College of Medicine, Seou (Korea, Republic of)
2013-01-15
The purpose of this study was to assess the clinical outcomes of hypofractionated radiotherapy (HFRT) with three-dimensional conformal technique for medically inoperable patients with early stage non-small-cell lung cancer (NSCLC) and to evaluate prognostic factors. We performed a retrospective review of 26 patients who underwent HFRT for early stage NSCLC between September 2005 and August 2011. Only clinical stage T1-3N0 was included. The median RT dose was 70 Gy (range, 60 to 72 Gy) and the median biologically equivalent dose (BED) was 94.5 Gy (range, 78.0 to 100.8 Gy). In 84.6% of patients, 4 Gy per fraction was used. Neoadjuvant chemotherapy with paclitaxel and cisplatin was given to 2 of 26 patients. The median follow-up time for surviving patients was 21 months (range, 13 to 49 months). The overall response rate was 53.9%, and the initial local control rate was 100%. The median survival duration was 27.8 months. Rates of 2-year overall survival, progression-free survival (PFS), local control (LC), and locoregional-free survival (LRFS) were 54.3%, 61.1%, 74.6%, and 61.9%, respectively. Multivariate analysis showed that BED (>90 vs. {<=}90 Gy) was an independent prognostic factor influencing PFS, LC, and LRFS. Severe toxicities over grade 3 were not observed. Radical HFRT can yield satisfactory disease control with acceptable rates of toxicities in medically inoperable patients with early stage NSCLC. HFRT is a viable alternative for clinics and patients ineligible for stereotactic ablative radiotherapy. BED over 90 Gy and 4 Gy per fraction might be appropriate for HFRT.
Preliminary results of three-dimensional conformal radiotherapy for non-small cell lung cancer
International Nuclear Information System (INIS)
Wang Yingjie; Wang Luhua; Wang Xin; Feng Qinfu; Zhang Hongxing; Xiao Zefen; Yin Weibo
2005-01-01
Objective: To evaluate the therapeutic effects and complications of three-dimensional conformal radiotherapy (3DCRT) for non-small cell lung cancer (NSCLC). Methods: Between March 1999 and September 2003, 91 NSCLC patients treated with 3DCRT were reviewed at the Cancer Hospital, Chinese Academy of Medical Sciences. This patient cohort consisted of 73 men and 18 women. The median age was 66 years. Radio-therapy was delivered at 2 Gy fraction, 5 fractions per week. The median total dose was 60 Gy. Results: With a median follow-up time of 17 months, the response rate after 3DCRT was 57.1%, with complete remission 11.0% (10/91) and partial remission 46.2%(42/91). The median survival time (MST) was 16 months, with 1- and 2- year overall survivals (OS) of 67.0% and 32.6%, 1- and 2-year local progression free survivals (LPFS) of 82.6% and 53.0%, respectively. The independent adverse prognostic factors by univariate analysis and multivariate analysis was weight loss ≥5%. Grade 2 acute radiation pneumonitis was observed in 2 patients and grade 3 in 4 patients. Late lung injury developed in 1 patient with grade 2, 1 patient with grade 3, respectively. Acute radiation esophagitis was observed in 8 patients with grade 2. Acute grade 2 hematologic toxicity developed in 5 patients. Conclusions: 3DCRT was feasible in the treatment of NSCLC with good immediate tumor response and acceptable normal tissue complication. The total dose may potentially be increased. (authors)
Setup error in three-dimensional conformal radiotherapy for thoracic esophageal carcinoma
International Nuclear Information System (INIS)
Hong Jinsheng; Zhang Weijian; Chen Jinmei; Cai Chuanshu; Ke Chunlin; Chen Xiuying; Wu Bing; Guo Feibao
2009-01-01
Objective: To study the setup errors in three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal carcinoma using electronic portal imaging device(EPID) and calculate the margins from CTV to PTV. Methods: Forty-one patients with thoracic esophageal carcinoma who received 3DCRT were continuously enrolled into this study. The anterior and lateral electronic portal images (EPI) were aquired by EPID once a week. The setup errors were obtained through comparing the difference between EPI and digitally reconstructed radiographs (DRR). Then the setup margins from CTV to PTV were calculated. By using self paired design, 22 patients received definitive radiotherapy with different margins. Group A: the margins were 10 mm in all the three axes; Group B: the margins were aquired in this study. The difference were compared by Paired t-test or Wilcoxon signed-rank test. Results: The margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. Between the group A and group B, the difference of the maximum dose of the spinal cord was significant(4638.7 cGy ± 1449.6 cGy vs. 4310.2 cGy ± 1528.7 cGy; t=5.48, P=0.000), and the difference of NTCP for the spinal cord was also significant (4.82% ± 5.99% vs. 3.64% ± 4.70%; Z=-2.70, P=0.007). Conclusions: For patients with thoracic esophageal carcinoma who receive 3DCRT in author's department, the margins from CTV to PTV in x, y and z axes were 8.72 mm, 10.50 mm and 5.62 mm, respectively. The spinal cord could be better protected by using these setup margins than using 10 mm in each axis. (authors)
International Nuclear Information System (INIS)
Jereczek-Fossa, B.A.; Orecchia, R.; Cattani, F.; Garibaldi, C.; Cambria, R.; Valenti, M.; Ciocca, M.; Zerini, D.; Boboc, G.I.; Vavassori, A.; Ivaldi, G.B.; Kowalczyk, A.; Matei, D.V.; Cobelli, O. de
2007-01-01
Purpose: To evaluate the feasibility and accuracy of daily B-mode acquisition and targeting ultrasound-based prostate localization (BAT trademark) and to compare it with computed tomography (CT) and electronic portal imaging (EPI) in 3-dimensional conformal radiotherapy (3-D CRT) for prostate cancer. Patients and Methods: Ten patients were treated with 3-D CRT (72 Gy/30 fractions, 2.4 Gy/fraction, equivalent to 80 Gy/40 fractions, for α/β ratio of 1.5 Gy) and daily BAT-based prostate localization. For the first 5 fractions, CT and EPI were also performed in order to compare organ-motion and set-up error, respectively. Results: 287 BAT-, 50 CT- and 46 EPI-alignments were performed. The average BAT-determined misalignments in latero-lateral, antero-posterior and cranio-caudal directions were -0.9 mm ± 3.3 mm, 1.0 mm ± 4.0 mm and -0.9 mm ± 3.8 mm, respectively. The differences between BAT- and CT-determined organ-motion in latero-lateral, antero-posterior and cranio-caudal directions were 2.7 mm ± 1.9 mm, 3.9 ± 2.8 mm and 3.4 ± 3.0 mm, respectively. Weak correlation was found between BAT- and CT-determined misalignments in antero-posterior direction, while no correlation was observed in latero-lateral and cranio-caudal directions. The correlation was more significant when only data of good image-quality patients were analyzed (8 patients). Conclusion: BAT ensures the relative positions of target are the same during treatment and in treatment plan, however, the reliability of alignment is patient-dependent. The average BAT-determined misalignments were small, confirming the prevalence of random errors in 3-D CRT. Further study is warranted in order to establish the clinical value of BAT. (orig.)
Estimating the costs of intensity-modulated and 3-dimensional conformal radiotherapy in Ontario.
Yong, J H E; McGowan, T; Redmond-Misner, R; Beca, J; Warde, P; Gutierrez, E; Hoch, J S
2016-06-01
Radiotherapy is a common treatment for many cancers, but up-to-date estimates of the costs of radiotherapy are lacking. In the present study, we estimated the unit costs of intensity-modulated radiotherapy (imrt) and 3-dimensional conformal radiotherapy (3D-crt) in Ontario. An activity-based costing model was developed to estimate the costs of imrt and 3D-crt in prostate cancer. It included the costs of equipment, staff, and supporting infrastructure. The framework was subsequently adapted to estimate the costs of radiotherapy in breast cancer and head-and-neck cancer. We also tested various scenarios by varying the program maturity and the use of volumetric modulated arc therapy (vmat) alongside imrt. From the perspective of the health care system, treating prostate cancer with imrt and 3D-crt respectively cost $12,834 and $12,453 per patient. The cost of radiotherapy ranged from $5,270 to $14,155 and was sensitive to analytic perspective, radiation technique, and disease site. Cases of head-and-neck cancer were the most costly, being driven by treatment complexity and fractions per treatment. Although imrt was more costly than 3D-crt, its cost will likely decline over time as programs mature and vmat is incorporated. Our costing model can be modified to estimate the costs of 3D-crt and imrt for various disease sites and settings. The results demonstrate the important role of capital costs in studies of radiotherapy cost from a health system perspective, which our model can accommodate. In addition, our study established the need for future analyses of imrt cost to consider how vmat affects time consumption.
International Nuclear Information System (INIS)
Caudrelier, Jean-Michel; Vial, Stephane; Gibon, David; Kulik, Carine; Fournier, Charles; Castelain, Bernard; Coche-Dequeant, Bernard; Rousseau, Jean
2003-01-01
Purpose: Three-dimensional (3D) volume determination is one of the most important problems in conformal radiation therapy. Techniques of volume determination from tomographic medical imaging are usually based on two-dimensional (2D) contour definition with the result dependent on the segmentation method used, as well as on the user's manual procedure. The goal of this work is to describe and evaluate a new method that reduces the inaccuracies generally observed in the 2D contour definition and 3D volume reconstruction process. Methods and Materials: This new method has been developed by integrating the fuzziness in the 3D volume definition. It first defines semiautomatically a minimal 2D contour on each slice that definitely contains the volume and a maximal 2D contour that definitely does not contain the volume. The fuzziness region in between is processed using possibility functions in possibility theory. A volume of voxels, including the membership degree to the target volume, is then created on each slice axis, taking into account the slice position and slice profile. A resulting fuzzy volume is obtained after data fusion between multiorientation slices. Different studies have been designed to evaluate and compare this new method of target volume reconstruction and a classical reconstruction method. First, target definition accuracy and robustness were studied on phantom targets. Second, intra- and interobserver variations were studied on radiosurgery clinical cases. Results: The absolute volume errors are less than or equal to 1.5% for phantom volumes calculated by the fuzzy logic method, whereas the values obtained with the classical method are much larger than the actual volumes (absolute volume errors up to 72%). With increasing MRI slice thickness (1 mm to 8 mm), the phantom volumes calculated by the classical method are increasing exponentially with a maximum absolute error up to 300%. In contrast, the absolute volume errors are less than 12% for phantom
Chui, S. T.; Chen, Xinzhong; Liu, Mengkun; Lin, Zhifang; Zi, Jian
2018-02-01
We study the response of a conical metallic surface to an external electromagnetic (em) field by representing the fields in basis functions containing the integrable singularity at the tip of the cone. A fast analytical solution is obtained by the conformal mapping between the cone and a round disk. We apply our calculation to the scattering-type scanning near-field optical microscope (s-SNOM) and successfully quantify the elastic light scattering from a vibrating metallic tip over a uniform sample. We find that the field-induced charge distribution consists of localized terms at the tip and the base and an extended bulk term along the body of the cone far away from the tip. In recent s-SNOM experiments at the visible and infrared range (600 nm to 1 μ m ) the fundamental of the demodulated near-field signal is found to be much larger than the higher harmonics whereas at THz range (100 μ m to 3 mm) the fundamental becomes comparable to the higher harmonics. We find that the localized tip charge dominates the contribution to the higher harmonics and becomes larger for the THz experiments, thus providing an intuitive understanding of the origin of the near-field signals. We demonstrate the application of our method by extracting a two-dimensional effective dielectric constant map from the s-SNOM image of a finite metallic disk, where the variation comes from the charge density induced by the em field.
Directory of Open Access Journals (Sweden)
Jiang Hualiang
2010-11-01
Full Text Available Abstract Background Conformational sampling for small molecules plays an essential role in drug discovery research pipeline. Based on multi-objective evolution algorithm (MOEA, we have developed a conformational generation method called Cyndi in the previous study. In this work, in addition to Tripos force field in the previous version, Cyndi was updated by incorporation of MMFF94 force field to assess the conformational energy more rationally. With two force fields against a larger dataset of 742 bioactive conformations of small ligands extracted from PDB, a comparative analysis was performed between pure force field based method (FFBM and multiple empirical criteria based method (MECBM hybrided with different force fields. Results Our analysis reveals that incorporating multiple empirical rules can significantly improve the accuracy of conformational generation. MECBM, which takes both empirical and force field criteria as the objective functions, can reproduce about 54% (within 1Å RMSD of the bioactive conformations in the 742-molecule testset, much higher than that of pure force field method (FFBM, about 37%. On the other hand, MECBM achieved a more complete and efficient sampling of the conformational space because the average size of unique conformations ensemble per molecule is about 6 times larger than that of FFBM, while the time scale for conformational generation is nearly the same as FFBM. Furthermore, as a complementary comparison study between the methods with and without empirical biases, we also tested the performance of the three conformational generation methods in MacroModel in combination with different force fields. Compared with the methods in MacroModel, MECBM is more competitive in retrieving the bioactive conformations in light of accuracy but has much lower computational cost. Conclusions By incorporating different energy terms with several empirical criteria, the MECBM method can produce more reasonable conformational
Dosimetric evaluation of the conformation of the multileaf collimator to irregularly shaped fields
International Nuclear Information System (INIS)
Frazier, Arthur; Du, Maria; Wong, John; Vicini, Frank; Taylor, Roy; Yu, Cedric; Matter, Richard; Martinez, Alvaro; Yan Di
1995-01-01
Purpose: The goal of this study was to evaluate the dosimetric characteristics of geometric MLC prescription strategies and compare them to those of conventional shielding block. Methods and Materials: Circular fields, square fields, and 12 irregular fields for patients with cancer of the head and neck, lung, and pelvis were included in this study. All fields were shaped using the MLC and conventional blocks. A geometric criterion was defined as the amount of area discrepancy between the MLC and the prescription outline. The 'least area discrepancy' (LAD) of the MLC conformation was searched by selecting the collimator angle, meanwhile keeping a preselected position along the width of the leaf into the prescribed field. Five LAD conventions were studied. These included the LAD-0, LAD-(1(3)), LAD-(1(2)), and LAD-(2(3)) that inserted the leaves at the 0, (1(3)), (1(2)), and (2(3)) of the leaf end into the prescription field, respectively. In addition, the LAD optimization was applied to the transecting (TRN) approach for leaf conformation that prescribed an equal area of overblocking and underblocking under each leaf. Film dosimetry was performed in a 20 cm polystyrene phantom at 10 cm depth 100 cm from source to axis distance (SAD) for both 6 and 18 MV photons with each of the above MLC conformations and conventional blocks. The field penumbra width, defined as the mean of the separation between the 20% and 80% isodose lines along the normal of the prescription field edge, was calculated using both the MLC and conventional block film dosimetry and compared. In a similar way, the d20 is defined as the mean separation between the 20% isodose line and the prescription field edge, and the d80 is defined as the mean separation between the 80% isodose line and the prescription field edge. Results: The field penumbra width for all MLC conventions was approximately 2 mm larger than that of the conventional block. However, there was a larger variation of the separation
Implications of conformal invariance for quantum field theories in d>2
International Nuclear Information System (INIS)
Osborn, H.
1994-01-01
Recently obtained results for two and three point functions for quasi-primary operators in conformally invariant theories in arbitrary dimensions d are described. As a consequence the three point function for the energy momentum tensor has three linearly independent forms for general d compatible with conformal invariance. The corresponding coefficients may be regarded as possible generalisations of the Virasoro central charge to d larger than 2. Ward identities which link two linear combinations of the coefficients to terms appearing in the energy momentum tensor trace anomaly on curved space are discussed. The requirement of positivity for expectation values of the energy density is also shown to lead to positivity conditions which are simple for a particular choice of the three coefficients. Renormalisation group like equations which express the constraints of broken conformal invariance for quantum field theories away from critical points are postulated and applied to two point functions. (orig.)
Directory of Open Access Journals (Sweden)
Sun Zong-wen
2018-01-01
Full Text Available Introduction. All adult medulloblastoma (AMB patients should be treated with craniospinal irradiation (CSI postoperatively. Because of the long irradiation range, multiple radiation fields must be designed for conventional radiotherapy technology. CSI can be completed in only one session with helical tomotherapy (HT. We evaluated the dose of HT, volumetric intensity modulated arc therapy (VMAT, and three-dimensional conformal radiotherapy (3D-CRT of AMB and the results of 5 cases of AMB treated with HT. Methods. Complete craniospinal and posterior cranial fossa irradiation with HT, VMAT, and 3D-CRT and dose evaluation were performed. And results of 5 cases of AMB treated with HT were evaluated. Results. A large volume of tissue was exposed to low dose radiation in the organs at risk (OAR, while a small volume was exposed to high dose radiation with HT. The conformity and uniformity of the targets were good with HT and VMAT, and the volume of targets exposed to high dose with VMAT was larger than that of HT. The uniformity of 3D-CRT was also good, but the dose conformity was poor. The main toxicity was hematologic toxicity, without 4th-degree bone marrow suppression. There was 3rd-degree inhibition in the white blood cells, hemoglobin, and platelets. The three female patients suffered menstrual disorders during the course of radiation. Two female patients with heavy menstruation suffered 3rd-degree anemia inhibition, and 2 patients suffered amenorrhea after radiotherapy. Although menstrual cycle was normal, the third patient was not pregnant. Conclusion. CSI with HT is convenient for clinical practice, and the side effects are mild. With good conformity and uniformity, VMAT can also be used for selection in CSI. For poor conformity, 3D-CRT should not be the priority selection for CSI. In female patients, the ovaries should be protected.
International Nuclear Information System (INIS)
Accioly, A.J.
1985-01-01
Exact solutions of the Einstein-Conformally Invariant Scalar Field Equations are obtained for Kantowski-Sachs and Bianchi types I and III cosmologies. The presence of the conformally invariant scalar field is responsible for some interesting features of the solutions. In particular it is found that the Bianchi I model is consistent with the big-bang theory of cosmology. (Author) [pt
International Nuclear Information System (INIS)
Ding Meisong; Newman, Francis M.S.; Kavanagh, Brian D.; Stuhr, Kelly M.S.; Johnson, Tim K.; Gaspar, Laurie E.
2006-01-01
Purpose: To investigate the dosimetric differences among three-dimensional conformal radiotherapy (3D-CRT), dynamic conformal arc therapy (DCAT), and intensity-modulated radiotherapy (IMRT) for brain tumor treatment. Methods and Materials: Fifteen patients treated with Novalis were selected. We performed 3D-CRT, DCAT, and IMRT plans for all patients. The margin for the planning target volume (PTV) was 1 mm, and the specific prescription dose was 90% for all plans. The target coverage at the prescription dose, conformity index (CI), and heterogeneity index were analyzed for all plans. Results: For small tumors (PTV ≤2 cm 3 ), the three dosimetric parameters had approximate values for both 3D-CRT and DCAT plans. The CI for the IMRT plans was high. For medium tumors (PTV >2 to ≤100 cm 3 ), the three plans were competitive with each other. The IMRT plans had a greater CI, better target coverage at the prescription dose, and a better heterogeneity index. For large tumors (PTV >100 cm 3 ), the IMRT plan had good target coverage at the prescription dose and heterogeneity index and approximate CI values as those in the 3D-CRT and DCAT plans. Conclusion: The results of our study have shown that DCAT is suitable for most cases in the treatment of brain tumors. For a small target, 3D-CRT is useful, and IMRT is not recommended. For larger tumors, IMRT is superior to 3D-CRT and very competitive in sparing critical structures, especially for big tumors
International Nuclear Information System (INIS)
Jin Feng; Ouyang Jinling; Dong Hongmin; Wu Weili; Chen Haixia; He Zhihui
2005-01-01
Objective: To compare the therapeutic effects, toxic side effects of late-course three dimensional conformal radiotherapy plus chrono-chemotherapy (DDP + 5-FU/CF) and conventional radiotherapy plus chemotherapy for nasopharyngeal carcinoma (NPC). Methods: Eighty -six NPC patients admitted from Feb. 2001 to Jan. 2002 were divided randomly into two groups: 1. Chrono-chemotherapy + late course three dimensional conformal radiotherapy(CCR) group-44 patients were treated by late course three dimensional conformal radio-therapy plus chrono-chemotherapy, and 2. Routine-chemotherapy-radiotherapy (RCR) group-42 patients were treated by routine chemotherapy plus radiotherapy. The patients in CCR and RCR group were comparable in age, KPS, stage and pathology. All patients were treated by combined chemotherapy and radiotherapy, with chemotherapy stared 2 weeks ahead of radiotherapy. Chemotherapy: Braun pump was used in all drug infusions; 1. CCR group-DDP 80 mg/ m 2 starting from 10:00 until 22:00, 5-Fu 750 mg/d/m 2 starting from 22:00 until 10:00 next day, CF 200 mg/d/m 2 starting from 10:00 every day, infused at normal speed. These drugs were given for 3 days, 14 days as one cycle, totally 2 cycle, and 2. RCR group-with the same drugs at the same total dose, only with the difference being DDP and CF given QD, starting from 10:00 but at the normal speed. 5-Fu was given through-out the day and continuously for 3 days, totally for 2 cycles. Radiotherapy: linear accelerator irradiation was given to either group. Composite facio-cervical field + anterior cervical tangential field to D T 40 Gy/4w, followed by the coned down per-auricular field plus anterior tangential field or β beam irradiation. In CCR group, after D T 40gy/4w, late course 3-dimensional conformal radiotherapy (3DCRT) was used to add D T 30Gy/3w. In RCR group, routine radiotherapy of 40 Gy/w was supplemented with 30 Gy/3w. The total dose in either group was 70 Gy/7w at the nasopharynx, D T 60-70 Gy/6-7w at the
Towards a classification of fusion rule algebras in rational conformal field theories
International Nuclear Information System (INIS)
Ravanini, F.
1991-01-01
We review the main topics concerning Fusion Rule Algebras (FRA) of Rational Conformal Field Theories. After an exposition of their general properties, we examine known results on the complete classification for low number of fields (≤4). We then turn our attention to FRA's generated polynomially by one (real) fundamental field, for which a classification is known. Attempting to generalize this result, we describe some connections between FRA's and Graph Theory. The possibility to get new results on the subject following this ''graph'' approach is briefly discussed. (author)
Explicit Solutions for One-Dimensional Mean-Field Games
Prazeres, Mariana
2017-01-01
In this thesis, we consider stationary one-dimensional mean-field games (MFGs) with or without congestion. Our aim is to understand the qualitative features of these games through the analysis of explicit solutions. We are particularly interested
A three-dimensional field solutions of Halbach
International Nuclear Information System (INIS)
Chen Jizhong; Xiao Jijun; Zhang Yiming; Xu Chunyan
2008-01-01
A three-dimensional field solutions are presented for Halback cylinder magnet. Based on Ampere equivalent current methods, the permanent magnets are taken as distributing of current density. For getting the three-dimensional field solution of ideal polarized permanent magnets, the solution method entails the use of the vector potential and involves the closed-form integration of the free-space Green's function. The programmed field solution are ideal for performing rapid parametric studies of the dipole Halback cylinder magnets made from rare earth materials. The field solutions are verified by both an analytical two-dimensional algorithm and three-dimensional finite element software. A rapid method is presented for extensive analyzing and optimizing Halbach cylinder magnet. (authors)
Promising survival with three-dimensional conformal radiation therapy for non-small cell lung cancer
International Nuclear Information System (INIS)
Armstrong, John; Raben, Adam; Zelefsky, Michael; Burt, Michael; Leibel, Steve; Burman, Chandra; Kutcher, Gerard; Harrison, Louis; Hahn, Cathy; Ginsberg, Robert; Rusch, Valerie; Kris, Mark; Fuks, Zvi
1997-01-01
Purpose: Local failure is a major obstacle to the cure of locally advanced non small-cell lung cancer. Three-dimensional conformal radiation therapy (3-DCRT) selects optimal treatment parameters to increase dose to tumor and reduce normal tissue dose, potentially representing an enhancement of the therapeutic ratio of radiation therapy for lung cancer. We performed this analysis of 45 non-small cell lung cancer patients treated with 3-DCRT alone, to evaluate the ability of computer derived lung dose volume histograms to predict serious pulmonary toxicity, to assess the feasibility of this approach, and to examine the resulting survival. Methods: There were 28 males (62%) and 17 females (38%). The median age was 65 (range: 38-82). Tumor stage was Stage I/II in 13%, IIIa in 42%, and IIIb in 44%. The histology was squamous in 44%, adenocarcinoma in 36%, and other non-small cell histologies in the others. Only 47% of patients. had combined favorable prognostic factors (i.e. KPS ≤ 80, and ≤5% wt. loss). The median dose of radiation to gross disease was 70.2 Gy (range: 52.2-72 Gy) delivered in fractions of 1.8 Gy, 5 days per week. Results: Seven patients did not complete 3-DCRT due to disease progression outside the port. Follow-up data are mature: the median follow up of the 6 survivors is 43.5 months (35-59). Thoracic progression occurred in 46%. Median survival (all 45 patients.) is 15.7 months and survival is 32% at 2 years and 12% at 59 months. Pulmonary toxicity ≥grade 3 occurred in 9% of patients. Dose volume histograms were available in 31 patients and showed a correlation between risk of pulmonary toxicity and indices of dose to lung parenchyma. Grade 3 or higher pulmonary toxicity occurred in 38% ((3(8))) of patients with >30% of lung volume receiving ≥25 Gy, versus 4% ((1(23))) of patients with ≤30% lung receiving ≥25 Gy (P = 0.04). Grade 3 or higher pulmonary toxicity occurred in 29% ((4(14))) of patients with a predicted pulmonary normal tissue
Gibbs perturbations of a two-dimensional gauge field
International Nuclear Information System (INIS)
Petrova, E.N.
1981-01-01
Small Gibbs perturbations of random fields have been investigated up to now for a few initial fields only. Among them there are independent fields, Gaussian fields and some others. The possibility for the investigation of Gibbs modifications of a random field depends essentially on the existence of good estimates for semiinvariants of this field. This is the reason why the class of random fields for which the investigation of Gibbs perturbations with arbitrary potential of bounded support is possible is rather small. The author takes as initial a well-known model: a two-dimensional gauge field. (Auth.)
International Nuclear Information System (INIS)
Kam, M.; Shafer, R.H.; Berman, E.
1988-01-01
A conformational analysis and a complete assignment of the nonexchangeable proton resonances of chromomycin A 3 , dechromose-A chromomycin A 3 , and deacetylchromose-B chromomycin A 3 were carried out in organic solvents. The resulting conformation in methanol has the three side chains of chromomycin A 3 fully extended, away from one another and from the aglycon. In dichloromethane on the other hand, the drug was shown to adopt a highly compact conformation in which most of the 26 oxygen atoms in the molecule point out toward the solvent. The two carbohydrate side chains extend parallel to each other on the same side of the aglycon. Two intramolecular nuclear Overhauser enhancement contacts have been observed between different sugar units on these side chains, indicating close proximity for these moieties. In addition, the aliphatic side chain is folded toward the aglycon, parallel to the two oligosaccharide side chains. The overall conformation has a wedge-like shape with the two phenoxy groups exposed at the pointed edge. The presence of some exchange cross-peaks in the NOESY spectra suggests the presence of intramolecular hydrogen bonds that probably help to maintain the compact information. The derivatives of chromomycin A 3 have qualitatively similar conformations, though their respective conformations are not as compact as the parent drug. The significance of these results is discussed in terms of a model of chromomycin A 3 binding to DNA in the major groove
BCS wave function, matrix product states, and the Ising conformal field theory
Montes, Sebastián; Rodríguez-Laguna, Javier; Sierra, Germán
2017-11-01
We present a characterization of the many-body lattice wave functions obtained from the conformal blocks (CBs) of the Ising conformal field theory (CFT). The formalism is interpreted as a matrix product state using continuous ancillary degrees of freedom. We provide analytic and numerical evidence that the resulting states can be written as BCS states. We give a complete proof that the translationally invariant 1D configurations have a BCS form and we find suitable parent Hamiltonians. In particular, we prove that the ground state of the finite-size critical Ising transverse field (ITF) Hamiltonian can be obtained with this construction. Finally, we study 2D configurations using an operator product expansion (OPE) approximation. We associate these states to the weak pairing phase of the p +i p superconductor via the scaling of the pairing function and the entanglement spectrum.
International Nuclear Information System (INIS)
Ishimoto, Yukitaka
2004-01-01
Amongst conformal field theories, there exist logarithmic conformal field theories such as c p,1 models. We have investigated c p,q models with a boundary in search of logarithmic theories and have found logarithmic solutions of two-point functions in the context of the Coulomb gas picture. We have also found the relations between coefficients in the two-point functions and correlation functions of logarithmic boundary operators, and have confirmed the solutions in [hep-th/0003184]. Other two-point functions and boundary operators have also been studied in the free boson construction of boundary CFT with SU(2) k symmetry in regard to logarithmic theories. This paper is based on a part of D. Phil. Thesis [hep-th/0312160]. (author)
Direct approach to operator conformal constructions: from fermions to primary fields
International Nuclear Information System (INIS)
Halpern, M.B.
1989-01-01
I discuss the direct solution of Sugawara and coset constructions, including a path to construction of the primary fields. The basic tools are (1) a construction of affine-conformal highest-weight states, pretensors and tensors form quantum-irreducible representations of the currents of affine g, and (2) construction of primary fields by factorization and boosting of the pretensors. Large classes of pretensors are easily obtained in fermionic constructions, and guesswork is minimized with factorization of bosonized fermionic pretensors: The simplest case constructs conformal-weights h g =mN(n--N)/2n of SU m (n) and h K =mN(n--N)/n of SU m (n)direct-product SU m (n)/SU 2m (n) and extension to simply-laced g is clear. More general cases are left for future study. copyright Academic Prss, Inc. 1989
International Nuclear Information System (INIS)
Kim, Hae Young; Huh, Seung Jae; Park, Won; Choi, Do Ho; Kang, Min Kyu; Yang, Jung Hyun; Nam, Seok Jin; Im, Young Hyuck
2008-01-01
To evaluate the response and survival rate after three-dimensional conformal radiation therapy (3D-CRT) of patients with a solitary sternal relapse of breast cancer. Seventeen patients between May 1996 and June 2005 were evaluated with the salvage 3D-CRT treatment of a solitary sternal relapse of breast cancer. The treatment fields included the gross tumor volume with 2 cm margins. The total radiation dose was 35.0 ∼61.5 Gy (biologic effective dose of 43.7 ∼76.9 Gy10 using an α/β ratio of 10 Gy), with a daily dose of 1.8∼3.0 Gy. The tumor response was evaluated by the change in maximum tumor size via follow up CT scans 1∼3 months after the completion of treatment. An objective tumor response was achieved in all patients, with a complete response in 5 patients and a partial response in 12 patients. The 5-year overall survival rate was 51.9% (median survival time: 27 months), and the most important factor affecting overall survival was the disease-free interval (interval from primary surgery of breast cancer to the development of sternal metastasis): The 5-year overall survival rate was 61.8% for patients with a disease-free interval ≥12 months and 0.0% for patients < with disease-free interval <12 months (p=0.03). The response to 3D-CRT was good in patients with solitary sternal relapse of breast cancer. Particularly, patients with long disease-free interval from primary surgery survived significantly longer than patients with short disease-free interval from primary surgery
Contour integral representations for the characters of rational conformal field theories
International Nuclear Information System (INIS)
Mukhi, S.; Panda, S.; Sen, A.
1989-01-01
We propose simple Feigin-Fuchs contour integral representations for the characters of a large class of rational conformal field theories. These include the A, D and E series SU(2) WZW theories, the A and D series c<1 minimal theories, and the k=1 SU(N) WZW theories. All these theories are characterized by the absence of the zeroes in the wronskian determinant of the characters in the interior of moduli space. This proposal is verified by several calculations. (orig.)
International Nuclear Information System (INIS)
Souza Alves, Marcelo de.
1990-03-01
Some general aspects on field theories in curved space-time and a introduction to conformal symmetry are presented.The behavior of the physical systems under Weyl transformations is discussed. The quantization of such systems are performed through the functional integration method. The regularization in curved space-time is also discussed. An application of this analysis in String theories is made. 42 refs
Coding for Two Dimensional Constrained Fields
DEFF Research Database (Denmark)
Laursen, Torben Vaarbye
2006-01-01
a first order model to model higher order constraints by the use of an alphabet extension. We present an iterative method that based on a set of conditional probabilities can help in choosing the large numbers of parameters of the model in order to obtain a stationary model. Explicit results are given...... for the No Isolated Bits constraint. Finally we present a variation of the encoding scheme of bit-stuffing that is applicable to the class of checkerboard constrained fields. It is possible to calculate the entropy of the coding scheme thus obtaining lower bounds on the entropy of the fields considered. These lower...... bounds are very tight for the Run-Length limited fields. Explicit bounds are given for the diamond constrained field as well....
Tensor categories and the mathematics of rational and logarithmic conformal field theory
International Nuclear Information System (INIS)
Huang, Yi-Zhi; Lepowsky, James
2013-01-01
We review the construction of braided tensor categories and modular tensor categories from representations of vertex operator algebras, which correspond to chiral algebras in physics. The extensive and general theory underlying this construction also establishes the operator product expansion for intertwining operators, which correspond to chiral vertex operators, and more generally, it establishes the logarithmic operator product expansion for logarithmic intertwining operators. We review the main ideas in the construction of the tensor product bifunctors and the associativity isomorphisms. For rational and logarithmic conformal field theories, we review the precise results that yield braided tensor categories, and in the rational case, modular tensor categories as well. In the case of rational conformal field theory, we also briefly discuss the construction of the modular tensor categories for the Wess–Zumino–Novikov–Witten models and, especially, a recent discovery concerning the proof of the fundamental rigidity property of the modular tensor categories for this important special case. In the case of logarithmic conformal field theory, we mention suitable categories of modules for the triplet W-algebras as an example of the applications of our general construction of the braided tensor category structure. (review)
International Nuclear Information System (INIS)
Hislop, P.D.
1988-01-01
The Tomita modular operators and the duality property for the local von Neumann algebras in quantum field models describing free massless particles with arbitrary helicity are studied. It is proved that the representation of the Poincare group in each model extends to a unitary representation of SU(2, 2), a covering group of the conformal group. An irreducible set of ''standard'' linear fields is shown to be covariant with respect to this representation. The von Neumann algebras associated with wedge, double-cone, and lightcone regions generated by these fields are proved to be unitarily equivalent. The modular operators for these algebras are obtained in explicit form using the conformal covariance and the results of Bisognano and Wichmann on the modular structure of the wedge algebras. The modular automorphism groups are implemented by one-parameter groups of conformal transformations. The modular conjugation operators are used to prove the duality property for the double-cone algebras and the timelike duality property for the lightcone algebras. copyright 1988 Academic Press, Inc
Kwon, Young Woo; Park, Junyong; Kim, Taehoon; Kang, Seok Hee; Kim, Hyowook; Shin, Jonghwa; Jeon, Seokwoo; Hong, Suck Won
2016-04-26
Multilevel hierarchical platforms that combine nano- and microstructures have been intensively explored to mimic superior properties found in nature. However, unless directly replicated from biological samples, desirable multiscale structures have been challenging to efficiently produce to date. Departing from conventional wafer-based technology, new and efficient techniques suitable for fabricating bioinspired structures are highly desired to produce three-dimensional architectures even on nonplanar substrates. Here, we report a facile approach to realize functional nanostructures on uneven microstructured platforms via scalable optical fabrication techniques. The ultrathin form (∼3 μm) of a phase grating composed of poly(vinyl alcohol) makes the material physically flexible and enables full-conformal contact with rough surfaces. The near-field optical effect can be identically generated on highly curved surfaces as a result of superior conformality. Densely packed nanodots with submicron periodicity are uniformly formed on microlens arrays with a radius of curvature that is as low as ∼28 μm. Increasing the size of the gratings causes the production area to be successfully expanded by up to 16 in(2). The "nano-on-micro" structures mimicking real compound eyes are transferred to flexible and stretchable substrates by sequential imprinting, facilitating multifunctional optical films applicable to antireflective diffusers for large-area sheet-illumination displays.
Conformal anomalies in curved space--time
Energy Technology Data Exchange (ETDEWEB)
Duncan, A.
1976-11-01
The general form of the conformal anomaly in a dimensionally regularized theory of massless fermions in a background metric is shown to be determined by the first few terms of weak field perturbation theory.
International Nuclear Information System (INIS)
Bondiau, P.Y.; Thariat, J.; Benezery, K.; Herault, J.; Dalmasso, C.; Marcie, S.; Malandain, G.
2007-01-01
The stereotaxic radiotherapy robotized by 'Cyberknife fourth generation' allows a dosimetric optimization with a high conformity index on the tumor and radiation doses limited on organs at risk. A cerebral automatic anatomic segmentation atlas of organs at risk are used in routine in three dimensions. This study evaluated the superiority of the stereotaxic radiotherapy in comparison with the three dimensional conformal radiotherapy on the preservation of organs at risk in regard of the delivered dose to tumors justifying an accelerated hypo fractionation and a dose escalation. This automatic segmentation atlas should allow to establish correlations between anatomy and cerebral dosimetry; This atlas allows to underline the dosimetry optimization by stereotaxic radiotherapy robotized for organs at risk. (N.C.)
Electromagnetic field in higher-dimensional black-hole spacetimes
International Nuclear Information System (INIS)
Krtous, Pavel
2007-01-01
A special test electromagnetic field in the spacetime of the higher-dimensional generally rotating NUT-(anti-)de Sitter black hole is found. It is adjusted to the hidden symmetries of the background represented by the principal Killing-Yano tensor. Such an electromagnetic field generalizes the field of charged black hole in four dimensions. In higher dimensions, however, the gravitational backreaction of such a field cannot be consistently solved
A note on the algebraic evaluation of correlators in local chiral conformal field theory
International Nuclear Information System (INIS)
Honecker, A.
1992-09-01
We comment on a program designed for the study of local chiral algebras and their representations in 2D conformal field theory. Based on the algebraic approach described by W. Nahm, this program efficiently calculates arbitrary n-point functions of these algebras. The program is designed such that calculations involving e.g. current algebras, W-algebras and N-Superconformal algebras can be performed. As a non-trivial application we construct an extension of the Virasoro algebra by two fields with spin four and six using the N=1-Super-Virasoro algebra. (orig.)
Stationary vacuum fields with a conformally flat three-space Pt. 1
International Nuclear Information System (INIS)
Lukacs, B.; Perjes, Z.; Sebestyen, A.; Sparling, G.A.J.
1982-01-01
A generalized notion of conformastat space-times is introduced in relativity theory. In this sense, the conformastat space-time is stationary with the three-space of time-like Killing trajectories being conformally flat. A 3+1 decomposition of the field equations is given, and two classes of nonstatic conformastat vacuum fields are exhaustively investigated. The resulting three metrics form a NUT-type extension of the solution of the static conformastat vacuum problem. The authors conjecture that all conformastat vacuum space-times are axially symmetric. (author)
International Nuclear Information System (INIS)
Yamaguchi, Shinsaku; Ohguri, Takayuki; Imada, Hajime
2011-01-01
The purpose of this study was to assess the toxicity and efficacy of multimodal approaches, including three-dimensional conformal re-irradiation, for patients with recurrent or persistent esophageal cancer after radiotherapy. Thirty-one patients with esophageal cancer treated with three-dimensional conformal re-irradiation were retrospectively analyzed. Of the 31 patients, 27 patients received concurrent chemotherapy, and 14 patients underwent regional hyperthermia during the re-irradiation. We divided the patients into two groups on the basis of their clinical condition: the curative group (n=11) or the palliative group (n=20). Severe toxicities were detected in one patient with Grade 3 esophageal perforation in the curative group, and 5 patients had a Grade 3 or higher toxicity of the esophagus in the palliative group. Advanced T stage at the time of re-irradiation was found to be significantly correlated with Grade 3 or higher toxicity in the esophagus. For the curative group, 10 (91%) of 11 patients had an objective response. For the palliative group, symptom relief was recognized in 8 (57%) of 14 patients with obvious swallowing difficulty. In conclusion, in the curative group with early-stage recurrent or persistent esophageal cancer, the multimodal approaches, including three-dimensional conformal re-irradiation, may be feasible, showing acceptable toxicity and a potential value of promising results, although further evaluations especially for the toxicities of the organs at risk are required. In the palliative group, the benefit of our therapy may be restrictive because severe esophageal toxicities were not uncommon in the patients with advanced T stage at the time of re-irradiation. (author)
International Nuclear Information System (INIS)
Israel, D.; Pakman, A.; Troost, J.
2004-01-01
We define extended SL(2,R)/U(1) characters which include a sum over winding sectors. By embedding these characters into similarly extended characters of N=2 algebras, we show that they have nice modular transformation properties. We calculate the modular matrices of this simple but non-trivial non-rational conformal field theory explicitly. As a result, we show that discrete SL(2,R) representations mix with continuous SL(2,R) representations under modular transformations in the coset conformal field theory. We comment upon the significance of our results for a general theory of non-rational conformal field theories. (author)
Supersymmetric gauge theories, quantization of M{sub flat}, and conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Teschner, J.; Vartanov, G.S.
2013-02-15
We propose a derivation of the correspondence between certain gauge theories with N=2 supersymmetry and conformal field theory discovered by Alday, Gaiotto and Tachikawa in the spirit of Seiberg-Witten theory. Based on certain results from the literature we argue that the quantum theory of the moduli spaces of flat SL(2,R)-connections represents a nonperturbative ''skeleton'' of the gauge theory, protected by supersymmetry. It follows that instanton partition functions can be characterized as solutions to a Riemann-Hilbert type problem. In order to solve it, we describe the quantization of the moduli spaces of flat connections explicitly in terms of two natural sets of Darboux coordinates. The kernel describing the relation between the two pictures represents the solution to the Riemann Hilbert problem, and is naturally identified with the Liouville conformal blocks.
International Nuclear Information System (INIS)
Horwitz, Eric M.; Hanlon, Alexandra L.; Pinover, Wayne H.; Hanks, Gerald E.
1998-01-01
Purpose: We reviewed our institution's experience treating patients with nonpalpable PSA-detected prostate cancer with three-dimensional conformal radiation therapy (3DCRT) to determine prognostic factors that predict for biochemical-free survival (bNED) control and present the bNED control rates. Methods and Materials: Between May 1, 1990 and November 30, 1994, 160 patients with nonpalpable PSA-detected prostate cancer received 3DCRT at Fox Chase Cancer Center (median total dose 73 Gy; range: 67-78 Gy). bNED failure was defined as three consecutive increases in posttreatment PSA after achieving a nadir. bNED failure was recorded as the time midway between the nadir and the first consecutive rising PSA. Five-year actuarial rates of bNED control were calculated for pretreatment PSA (0-9.9 vs. 10-19.9 vs. ≥ 20 ng/ml), Gleason score (2-6 vs. 7-10), treatment field size (prostate vs. small pelvis), age ( 73 Gy) using Kaplan-Meier methods and compared using the Log rank test. The Cox model was used to multivariately establish independent predictors based on significant univariate factors. Median follow-up was 39 months (range: 2-84 months). Results: The 5-year actuarial rate of bNED control was 86% for the entire group of patients. The Cox Proportional Hazards model demonstrated that pretreatment PSA was an independent predictor of bNED control. Treatment field size was marginally predictive. There was no difference in bNED control when patients were stratified by the number of lobes positive for disease. Statistically different rates of bNED control were seen when the patients with nonpalpable disease were univariately compared to T2b and T2c patients. Three patients experienced Grade 3-4 genitourinary (GU) toxicity and 3 patients experienced Grade 3-4 gastrointestinal (GI) toxicity. Conclusions: Patients with nonpalpable PSA-detected prostate cancer can be effectively treated with 3DCRT with minimal morbidity and high rates of bNED control at 5 years. Pretreatment
Energy Technology Data Exchange (ETDEWEB)
Hong, C; Ju, S; Ahn, Y; Oh, D; Noh, J; Chung, K; Kim, J; Han, Y; Choi, D [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)
2014-06-01
Purpose: We investigated the dosimetric benefit and treatment efficiency of carotid-sparing TomoHelical (TH) three-dimensional conformal radiotherapy (3DCRT) for early glottic cancer. Methods: Computed tomography (CT) simulation was performed for 10 patients with early-stage (T1N0M0) glottic squamous cell carcinoma. The clinical target volume, planning target volume (PTV), carotid artery (CA), and spinal cord (SP) were delineated for each CT data set. Two-field 3DCRT (2F-3DCRT), three-field intensity-modulated radiation therapy (IMRT) (3F-IMRT), TomoHelical-IMRT (TH-IMRT), and TH-3DCRT plans were generated, with a total prescribed dose of 67.5 Gy in 30 fractions to the PTV for each patient. In order to evaluate plan quality, dosimetric characteristics were compared in terms of the conformity index (CI) and homogeneity index (HI) for the PTV, V35, V50, and V63 for the CAs and in terms of the maximum dose for the SP. Additionally, treatment planning and delivery times were compared to evaluate treatment efficiency. Results: The CIs for 3F-IMRT (0.650±0.05), TH-IMRT (0.643±0.03), and TH-3DCRT (0.631±0.03) were much better than that for 2F-3DCRT (0.318±0.03). The HIs for TH-IMRT (1.053±0.01) and TH-3DCRT (1.055±0.01) were slightly better than those for 2F-3DCRT (1.062±0.01) and 3F-IMRT (1.091±0.007). 2F-3DCRT showed poor CA sparing in terms of the V35, V50, and V63 compared to 3F-IMRT, TH-IMRT, and TH-3DCRT (p<0.05), whereas there was no significant dose difference between 3F-IMRT, TH-IMRT, and TH-3DCRT (p>0.05). The maximum dose to the SP with all plans was below 45 Gy. The treatment planning times for 2F-3DCRT (5.9±0.66 min) and TH-3DCRT (7.32±0.94 min) were much lower than those for 3F-IMRT (45.51±2.76 min) and TH-IMRT (35.58±4.41 min), whereas the delivery times with all plans was below 3 minutes. Conclusion: TH-3DCRT showed excellent carotid sparing capability, comparable to that with TH-IMRT, with high treatment efficiency and short planning and
Lee, Kuo Hao; Chen, Jianhan
2017-06-15
Accurate treatment of solvent environment is critical for reliable simulations of protein conformational equilibria. Implicit treatment of solvation, such as using the generalized Born (GB) class of models arguably provides an optimal balance between computational efficiency and physical accuracy. Yet, GB models are frequently plagued by a tendency to generate overly compact structures. The physical origins of this drawback are relatively well understood, and the key to a balanced implicit solvent protein force field is careful optimization of physical parameters to achieve a sufficient level of cancellation of errors. The latter has been hampered by the difficulty of generating converged conformational ensembles of non-trivial model proteins using the popular replica exchange sampling technique. Here, we leverage improved sampling efficiency of a newly developed multi-scale enhanced sampling technique to re-optimize the generalized-Born with molecular volume (GBMV2) implicit solvent model with the CHARMM36 protein force field. Recursive optimization of key GBMV2 parameters (such as input radii) and protein torsion profiles (via the CMAP torsion cross terms) has led to a more balanced GBMV2 protein force field that recapitulates the structures and stabilities of both helical and β-hairpin model peptides. Importantly, this force field appears to be free of the over-compaction bias, and can generate structural ensembles of several intrinsically disordered proteins of various lengths that seem highly consistent with available experimental data. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Finite action for three dimensional gravity with a minimally coupled scalar field
International Nuclear Information System (INIS)
Gegenberg, Jack; Martinez, Cristian; Troncoso, Ricardo
2003-01-01
Three-dimensional gravity with a minimally coupled self-interacting scalar is considered. The falloff of the fields at infinity is assumed to be slower than that of a localized distribution of matter in the presence of a negative cosmological constant. However, the asymptotic symmetry group remains to be the conformal group. The counterterm Lagrangian needed to render the action finite is found by demanding that the action attain an extremum for the boundary conditions implied by the above falloff of the fields at infinity. These counterterms explicitly depend on the scalar field. As a consequence, the Brown-York stress-energy tensor acquires a nontrivial contribution from the matter sector. Static circularly symmetric solutions with a regular scalar field are explored for a one-parameter family of potentials. Their masses are computed via the Brown-York quasilocal stress-energy tensor, and they coincide with the values obtained from the Hamiltonian approach. The thermal behavior, including the transition between different configurations, is analyzed, and it is found that the scalar black hole can decay into the Banados-Teitelboim-Zanelli solution irrespective of the horizon radius. It is also shown that the AdS conformal field theory correspondence yields the same central charge as for pure gravity
Energy Technology Data Exchange (ETDEWEB)
Poli, Ana Paula Diniz Fortuna, E-mail: anapaulafortuna@yahoo.com.br [Universidade Estadual de Campinas (CAISM/UNICAMP), Campinas, SP (Brazil). Centro de Atencao Integrada a Saude da Mulher. Divisao de Radioterapia; Dias, Rodrigo Souza; Giordani, Adelmo Jose; Segreto, Helena Regina Comodo; Segreto, Roberto Araujo [Universidade Federal de Sao Paulo (EPM/UNIFESP), Sao Paulo, SP (Brazil). Escola Paulista de Medicina. Divisao de Radioterapia
2016-01-15
Objective: To evaluate the rectal volume influence on prostate motion during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. Materials and Methods: Fifty-one patients with prostate cancer underwent a series of three computed tomography scans including an initial planning scan and two subsequent scans during 3D-CRT. The organs of interest were outlined. The prostate contour was compared with the initial CT images considering the anterior, posterior, superior, inferior and lateral edges of the organ. Variations in the anterior limits and volume of the rectum were assessed and correlated with prostate motion in the anteroposterior direction. Results: The maximum range of prostate motion was observed in the superoinferior direction, followed by the anteroposterior direction. A significant correlation was observed between prostate motion and rectal volume variation (p = 0.037). A baseline rectal volume superior to 70 cm{sup 3} had a significant influence on the prostate motion in the anteroposterior direction (p = 0.045). Conclusion: The present study showed a significant interfraction motion of the prostate during 3D-CRT with greatest variations in the superoinferior and anteroposterior directions, and that a large rectal volume influences the prostate motion with a cutoff value of 70 cm{sup 3}. Therefore, the treatment of patients with a rectal volume > 70 cm{sup 3} should be re-planned with appropriate rectal preparation. Keywords: Rectal volume; Prostate cancer; Three-dimensional conformal radiotherapy. (author)
Ververs, Patricia May
experimental findings. Attention was found to be more widely distributed in X-Y space when the pilots were flying with the conformal, tunnel-in-the-sky as compared to the partially conformal ILS (instrument landing system) symbology set. There was little evidence that the air-based navigation displays were supporting divided attention in three-dimensional space. The ground-based scene-linked (truly conformal) display indicated promising effects of dividing attention in depth without negative consequences to processing the near domain symbology. Event expectancy was found to modulate pilot performance in the detection of events both on the symbology and in the environment. The phenomenon known as cognitive tunneling is discussed as a possible cause of the inadequate response times in resolving the anomalous events.
Relative entropy of excited states in conformal field theories of arbitrary dimensions
Energy Technology Data Exchange (ETDEWEB)
Sárosi, Gábor [Theoretische Natuurkunde, Vrije Universiteit Brussels and International Solvay Institutes,Pleinlaan 2, Brussels, B-1050 (Belgium); David Rittenhouse Laboratory, University of Pennsylvania,Philadelphia, PA 19104 (United States); Ugajin, Tomonori [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)
2017-02-10
Extending our previous work, we study the relative entropy between the reduced density matrices obtained from globally excited states in conformal field theories of arbitrary dimensions. We find a general formula in the small subsystem size limit. When one of the states is the vacuum of the CFT, our result matches with the holographic entanglement entropy computations in the corresponding bulk geometries, including AdS black branes. We also discuss the first asymmetric part of the relative entropy and comment on some implications of the results on the distinguishability of black hole microstates in AdS/CFT.
Energy Technology Data Exchange (ETDEWEB)
Coelho, L A A [Programa de Pos-Graduacao em Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana, Rio de Janeiro, RJ, 20550-900 (Brazil); Skea, J E F [Departamento de Fisica Teorica, Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana, Rio de Janeiro, RJ, 20550-900 (Brazil); Stuchi, T J [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68528, Rio de Janeiro, RJ, 21945-970 (Brazil)], E-mail: luis@dft.if.uerj.br, E-mail: jimsk@dft.if.uerj.br, E-mail: tstuchi@if.ufrj.br
2008-02-22
In this paper, we use a nonintegrability theorem by Morales and Ramis to analyse the integrability of Friedmann-Robertson-Walker cosmological models with a conformally coupled massive scalar field. We answer the long-standing question of whether these models with a vanishing cosmological constant and non-self-interacting scalar field are integrable: by applying Kovacic's algorithm to the normal variational equations, we prove analytically and rigorously that these equations and, consequently, the Hamiltonians are nonintegrable. We then address the models with a self-interacting massive scalar field and cosmological constant and show that, with the exception of a set of measure zero, the models are nonintegrable. For the spatially curved cases, we prove that there are no additional integrable cases other than those identified in the previous work based on the non-rigorous Painleve analysis. In our study of the spatially flat model, we explicitly obtain a new possibly integrable case.
International Nuclear Information System (INIS)
Fogliata, Antonella; Cozzi, Luca; Bieri, Sabine; Bernier, Jacques
1999-01-01
Purpose: In head and neck cancer patients, spinal chains are usually irradiated by a combination of photon and electron beams, requiring high precision in field matching. This study compares a conventional treatment approach where two lateral photon beams are combined to direct electron fields, to a conformal radiotherapy based on five photon fields, covering the whole neck. Methods and Materials: A comparative analysis of dose distributions and dose-volume histograms was carried out in patients with locally advanced head and neck tumors, for which planning target volumes (PTV) were outlined from the base of the skull down to the supraclavicular region. The prescribed dose to PTV (excluding booster irradiation) was 54 Gy, with spinal dose constraint not exceeding 75% of the total dose, whatever the technique. Results: For the new five-field technique, minimum and maximum point doses showed mean deviations, on five patients entered in the study, of 84% and 113% from the ICRU prescription point. In the conventional treatment, the corresponding figures were 73% and 112%, respectively. A positioning error analysis (isocenter displacement of 2 mm, in all directions) did not elicit any systematic difference in five-field treatment plans while hot spots were found with electron fields. Conclusions: The five-field technique appears routinely feasible and compares favorably with the conventional mixed photon- and electron-therapy approach, especially in regard to its better compliance with dose homogeneity requirements and a reduced risk in dose inhomogeneity related to field matching and patient positioning
Conformal algebra of Riemann surfaces
International Nuclear Information System (INIS)
Vafa, C.
1988-01-01
It has become clear over the last few years that 2-dimensional conformal field theories are a crucial ingredient of string theory. Conformal field theories correspond to vacuum solutions of strings; or more precisely we know how to compute string spectrum and scattering amplitudes by starting from a formal theory (with a proper value of central charge of the Virasoro algebra). Certain non-linear sigma models do give rise to conformal theories. A lot of progress has been made in the understanding of conformal theories. The author discusses a different view of conformal theories which was motivated by the development of operator formalism on Riemann surfaces. The author discusses an interesting recent work from this point of view
Energy Technology Data Exchange (ETDEWEB)
Kole, Thomas P.; Aghayere, Osarhieme; Kwah, Jason [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Yorke, Ellen D. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Goodman, Karyn A., E-mail: goodmank@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
2012-08-01
Purpose: To compare heart and coronary artery radiation exposure using intensity-modulated radiotherapy (IMRT) vs. four-field three-dimensional conformal radiotherapy (3D-CRT) treatment plans for patients with distal esophageal cancer undergoing chemoradiation. Methods and Materials: Nineteen patients with distal esophageal cancers treated with IMRT from March 2007 to May 2008 were identified. All patients were treated to 50.4 Gy with five-field IMRT plans. Theoretical 3D-CRT plans with four-field beam arrangements were generated. Dose-volume histograms of the planning target volume, heart, right coronary artery, left coronary artery, and other critical normal tissues were compared between the IMRT and 3D-CRT plans, and selected parameters were statistically evaluated using the Wilcoxon rank-sum test. Results: Intensity-modulated radiotherapy treatment planning showed significant reduction (p < 0.05) in heart dose over 3D-CRT as assessed by average mean dose (22.9 vs. 28.2 Gy) and V30 (24.8% vs. 61.0%). There was also significant sparing of the right coronary artery (average mean dose, 23.8 Gy vs. 35.5 Gy), whereas the left coronary artery showed no significant improvement (mean dose, 11.2 Gy vs. 9.2 Gy), p = 0.11. There was no significant difference in percentage of total lung volume receiving at least 10, 15, or 20 Gy or in the mean lung dose between the planning methods. There were also no significant differences observed for the kidneys, liver, stomach, or spinal cord. Intensity-modulated radiotherapy achieved a significant improvement in target conformity as measured by the conformality index (ratio of total volume receiving 95% of prescription dose to planning target volume receiving 95% of prescription dose), with the mean conformality index reduced from 1.56 to 1.30 using IMRT. Conclusions: Treatment of patients with distal esophageal cancer using IMRT significantly decreases the exposure of the heart and right coronary artery when compared with 3D
International Nuclear Information System (INIS)
Sandler, Howard M.; McLaughlin, P. William; Ten Haken, Randall K.; Addison, Heather; Forman, Jeffrey; Lichter, Allen
1995-01-01
Purpose: Three dimensional conformal radiotherapy (3D CRT) may provide a technique to increase the dose delivered to target tissues while sparing uninvolved normal structures. To evaluate the role of 3D treatment in reducing the treatment toxicity, we analyzed the chronic rectal morbidity observed in a large group of patients undergoing radiotherapy for prostate cancer. Methods and Materials: From 1987 through 1992, 721 prostate cancer patients were treated with 3D CRT at the University of Michigan or Providence Hospital. All had axial computed tomography (CT) specifically for RT planning, multiple structures contoured on the axial images, and beam's-eye-view conformal beams edited to provide 3D dose coverage. Using current American Joint Commission (AJCC) staging, 537 patients had T1-T2 tumors, 123 had T3-T4 tumors, and 60 were treated postprostatectomy. Pelvic lymph nodes were treated in 462 patients. Prostate boosts were delivered with four-field axial, six-field axial, or four-field oblique, nonaxial fields. The median dose was 68.40 Gy (range 59.4-80.4). Median follow-up was 20.4 months; 175 were followed more than 3 years. All complications have been graded conservatively using the RTOG system. Results: Using a Cox proportional hazard's model, patient age, T-stage, prescribed dose, pelvic treatment, and boost technique were analyzed. The factor most strongly related to risk of morbidity was dose (p = 0.05); however, the boost technique was also related: the four-field oblique field had the lowest relative risk. Most episodes of rectal morbidity have been mild: 82 Grade 1 or 2. There have been only 14 more serious complications including 12 Grade 3 and 2 Grade 4. The actuarial risk of a Grade 3 or 4 complication is 3% at 3 and 5 years. Conclusions: A very small proportion of patients treated with 3D CRT had significant rectal morbidity related to RT, supporting the use of conformal treatment planning and dose delivery as a mechanism to minimize complications
Dimensional expansion for the Ising limit of quantum field theory
International Nuclear Information System (INIS)
Bender, C.M.; Boettcher, S.
1993-01-01
A recently proposed technique, called dimensional expansion, uses the space-time dimension D as an expansion parameter to extract nonperturbative results in quantum field theory. Here we apply dimensional-expansion methods to examine the Ising limit of a self-interacting scalar field theory. We compute the first few coefficients in the dimensional expansion of γ 2n , the renormalized 2n-point Green's function at zero momentum, for n=2, 3, 4, and 5. Because the exact results for γ 2n are known at D=1 we can compare the predictions of the dimensional expansion at this value of D. We find typical accuracies of less than 5%. The radius of convergence of the dimensional expansion for γ 2n appears to be 2n/(n-1). As a function of the space-time dimension D, γ 2n appears to rise monotonically with increasing D and we conjecture that it becomes infinite at D=2n/(n-1). We presume that for values of D greater than this critical value γ 2n vanishes identically because the corresponding φ 2n scalar quantum field theory is free for D>2n/(n-1)
Two-dimensional topological field theories coupled to four-dimensional BF theory
International Nuclear Information System (INIS)
Montesinos, Merced; Perez, Alejandro
2008-01-01
Four-dimensional BF theory admits a natural coupling to extended sources supported on two-dimensional surfaces or string world sheets. Solutions of the theory are in one to one correspondence with solutions of Einstein equations with distributional matter (cosmic strings). We study new (topological field) theories that can be constructed by adding extra degrees of freedom to the two-dimensional world sheet. We show how two-dimensional Yang-Mills degrees of freedom can be added on the world sheet, producing in this way, an interactive (topological) theory of Yang-Mills fields with BF fields in four dimensions. We also show how a world sheet tetrad can be naturally added. As in the previous case the set of solutions of these theories are contained in the set of solutions of Einstein's equations if one allows distributional matter supported on two-dimensional surfaces. These theories are argued to be exactly quantizable. In the context of quantum gravity, one important motivation to study these models is to explore the possibility of constructing a background-independent quantum field theory where local degrees of freedom at low energies arise from global topological (world sheet) degrees of freedom at the fundamental level
Efficient CT simulation of the four-field technique for conformal radiotherapy of prostate carcinoma
International Nuclear Information System (INIS)
Valicenti, Richard K.; Waterman, Frank M.; Croce, Raymond J.; Corn, Benjamin; Suntharalingam, Nagalingam; Curran, Walter J.
1997-01-01
Purpose: Conformal radiotherapy of prostate carcinoma relies on contouring of individual CT slices for target and normal tissue localization. This process can be very time consuming. In the present report, we describe a method to more efficiently localize pelvic anatomy directly from digital reconstructed radiographs (DRRs). Materials and Methods: Ten patients with prostate carcinoma underwent CT simulation (the spiral mode at 3 mm separation) for conformal four-field 'box' radiotherapy. The bulbous urethra and bladder were opacified with iodinated contrast media. On lateral and anteroposterior DRRs, the volume of interest (VOI) was restricted to 1.0-1.5 cm tissue thickness to optimize digital radiograph reconstruction of the prostate and seminal vesicles. By removing unessential voxel elements, this method provided direct visualization of those structures. For comparison, the targets of each patient were also obtained by contouring CT axial slices. Results: The method was successfully performed if the target structures were readily visualized and geometrically corresponded to those generated by contouring axial images. The targets in 9 of 10 patients were reliable representations of the CT-contoured volumes. One patient had 18 mm variation due to the lack of bladder opacification. Using VOIs to generate thin tissue DRRs, the time required for target and normal tissue localization was on the average less than 5 min. Conclusion: In CT simulation of the four-field irradiation technique for prostate carcinoma, thin-tissue DRRs allowed for efficient and accurate target localization without requiring individual axial image contouring. This method may facilitate positioning of the beam isocenter and provide reliable conformal radiotherapy
Topological black holes dressed with a conformally coupled scalar field and electric charge
International Nuclear Information System (INIS)
Martinez, Cristian; Troncoso, Ricardo; Staforelli, Juan Pablo
2006-01-01
Electrically charged solutions for gravity with a conformally coupled scalar field are found in four dimensions in the presence of a cosmological constant. If a quartic self-interaction term for the scalar field is considered, there is a solution describing an asymptotically locally AdS charged black hole dressed with a scalar field that is regular on and outside the event horizon, which is a surface of negative constant curvature. This black hole can have negative mass, which is bounded from below for the extremal case, and its causal structure shows that the solution describes a ''black hole inside a black hole''. The thermodynamics of the nonextremal black hole is analyzed in the grand canonical ensemble. The entropy does not follow the area law, and there is an effective Newton constant which depends on the value of the scalar field at the horizon. If the base manifold is locally flat, the solution has no electric charge, and the scalar field has a vanishing stress-energy tensor so that it dresses a locally AdS spacetime with a nut at the origin. In the case of vanishing self interaction, the solutions also dress locally AdS spacetimes, and if the base manifold is of negative constant curvature a massless electrically charged hairy black hole is obtained. The thermodynamics of this black hole is also analyzed. It is found that the bounds for the black holes parameters in the conformal frame obtained from requiring the entropy to be positive are mapped into the ones that guarantee cosmic censorship in the Einstein frame
Four dimensional sigma model coupled to the metric tensor field
International Nuclear Information System (INIS)
Ghika, G.; Visinescu, M.
1980-02-01
We discuss the four dimensional nonlinear sigma model with an internal O(n) invariance coupled to the metric tensor field satisfying Einstein equations. We derive a bound on the coupling constant between the sigma field and the metric tensor using the theory of harmonic maps. A special attention is paid to Einstein spaces and some new explicit solutions of the model are constructed. (author)
Three Dimensional Polarimetric Neutron Tomography of Magnetic Fields
DEFF Research Database (Denmark)
Sales, Morten; Strobl, Markus; Shinohara, Takenao
2018-01-01
Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non-destructively wi......Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non...... and reconstructed, thereby providing the proof-of-principle of a technique able to reveal hitherto unobtainable information on the magnetic fields in the bulk of materials and devices, due to a high degree of penetration into many materials, including metals, and the sensitivity of neutron polarisation to magnetic...... fields. The technique puts the potential of the ToF time structure of pulsed neutron sources to full use in order to optimise the recorded information quality and reduce measurement time....
Two-dimensional models in statistical mechanics and field theory
International Nuclear Information System (INIS)
Koberle, R.
1980-01-01
Several features of two-dimensional models in statistical mechanics and Field theory, such as, lattice quantum chromodynamics, Z(N), Gross-Neveu and CP N-1 are discussed. The problems of confinement and dynamical mass generation are also analyzed. (L.C.) [pt
Generation of a Desired Three-Dimensional Electromagnetic Field
DEFF Research Database (Denmark)
2005-01-01
The present invention relates to a method and a system for synthesizing a prescribed three-dimensional electromagnetic field based on generalized phase contrast imaging. Such a method and apparatus may be utilized in advanced optical micro and nano-manipulation, such as by provision of a multiple...
Noether symmetries, energy-momentum tensors, and conformal invariance in classical field theory
International Nuclear Information System (INIS)
Pons, Josep M.
2011-01-01
In the framework of classical field theory, we first review the Noether theory of symmetries, with simple rederivations of its essential results, with special emphasis given to the Noether identities for gauge theories. With this baggage on board, we next discuss in detail, for Poincare invariant theories in flat spacetime, the differences between the Belinfante energy-momentum tensor and a family of Hilbert energy-momentum tensors. All these tensors coincide on shell but they split their duties in the following sense: Belinfante's tensor is the one to use in order to obtain the generators of Poincare symmetries and it is a basic ingredient of the generators of other eventual spacetime symmetries which may happen to exist. Instead, Hilbert tensors are the means to test whether a theory contains other spacetime symmetries beyond Poincare. We discuss at length the case of scale and conformal symmetry, of which we give some examples. We show, for Poincare invariant Lagrangians, that the realization of scale invariance selects a unique Hilbert tensor which allows for an easy test as to whether conformal invariance is also realized. Finally we make some basic remarks on metric generally covariant theories and classical field theory in a fixed curved background.
Quantum Fluctuations and the Unruh effect in strongly-coupled conformal field theories
Cáceres, Elena; Chernicoff, Mariano; Güijosa, Alberto; Pedraza, Juan F.
2010-06-01
Through the AdS/CFT correspondence, we study a uniformly accelerated quark in the vacuum of strongly-coupled conformal field theories in various dimensions, and determine the resulting stochastic fluctuations of the quark trajectory. From the perspective of an inertial observer, these are quantum fluctuations induced by the gluonic radiation emitted by the accelerated quark. From the point of view of the quark itself, they originate from the thermal medium predicted by the Unruh effect. We scrutinize the relation between these two descriptions in the gravity side of the correspondence, and show in particular that upon transforming the conformal field theory from Rindler space to the open Einstein universe, the acceleration horizon disappears from the boundary theory but is preserved in the bulk. This transformation allows us to directly connect our calculation of radiation-induced fluctuations in vacuum with the analysis by de Boer et al. of the Brownian motion of a quark that is on average static within a thermal medium. Combining this same bulk transformation with previous results of Emparan, we are also able to compute the stress-energy tensor of the Unruh thermal medium.
Testing of a one dimensional model for Field II calibration
DEFF Research Database (Denmark)
Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten
2008-01-01
Field II is a program for simulating ultrasound transducer fields. It is capable of calculating the emitted and pulse-echoed fields for both pulsed and continuous wave transducers. To make it fully calibrated a model of the transducer’s electro-mechanical impulse response must be included. We...... examine an adapted one dimensional transducer model originally proposed by Willatzen [9] to calibrate Field II. This model is modified to calculate the required impulse responses needed by Field II for a calibrated field pressure and external circuit current calculation. The testing has been performed...... to the calibrated Field II program for 1, 4, and 10 cycle excitations. Two parameter sets were applied for modeling, one real valued Pz27 parameter set, manufacturer supplied, and one complex valued parameter set found in literature, Alguer´o et al. [11]. The latter implicitly accounts for attenuation. Results show...
International Nuclear Information System (INIS)
Hansen, Tobias
2015-07-01
This thesis covers two main topics: the tensorial structure of quantum field theory correlators in general spacetime dimensions and a method for computing string theory scattering amplitudes directly in target space. In the first part tensor structures in generic bosonic CFT correlators and scattering amplitudes are studied. To this end arbitrary irreducible tensor representations of SO(d) (traceless mixed-symmetry tensors) are encoded in group invariant polynomials, by contracting with sets of commuting and anticommuting polarization vectors which implement the index symmetries of the tensors. The tensor structures appearing in CFT d correlators can then be inferred by studying these polynomials in a d + 2 dimensional embedding space. It is shown with an example how these correlators can be used to compute general conformal blocks describing the exchange of mixed-symmetry tensors in four-point functions, which are crucial for advancing the conformal bootstrap program to correlators of operators with spin. Bosonic string theory lends itself as an ideal example for applying the same methods to scattering amplitudes, due to its particle spectrum of arbitrary mixed-symmetry tensors. This allows in principle the definition of on-shell recursion relations for string theory amplitudes. A further chapter introduces a different target space definition of string scattering amplitudes. As in the case of on-shell recursion relations, the amplitudes are expressed in terms of their residues via BCFW shifts. The new idea here is that the residues are determined by use of the monodromy relations for open string theory, avoiding the infinite sums over the spectrum arising in on-shell recursion relations. Several checks of the method are presented, including a derivation of the Koba-Nielsen amplitude in the bosonic string. It is argued that this method provides a target space definition of the complete S-matrix of string theory at tree-level in a at background in terms of a small
Rault, Erwann; Lacornerie, Thomas; Dang, Hong-Phuong; Crop, Frederik; Lartigau, Eric; Reynaert, Nick; Pasquier, David
2016-02-27
Accelerated partial breast irradiation (APBI) is a new breast treatment modality aiming to reduce treatment time using hypo fractionation. Compared to conventional whole breast irradiation that takes 5 to 6 weeks, APBI is reported to induce worse cosmetic outcomes both when using three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). These late normal tissue effects may be attributed to the dose volume effect because a large portion of the non-target breast tissue volume (NTBTV) receives a high dose. In the context of APBI, non-coplanar beams could spare the NTBTV more efficiently. This study evaluates the dosimetric benefit of using the Cyberknife (CK) for APBI in comparison to IMRT (Tomotherapy) and three dimensional conformal radiotherapy (3D-CRT). The possibility of using surgical clips, implanted during surgery, to track target movements is investigated first. A phantom of a female thorax was designed in-house using the measurements of 20 patients. Surgical clips of different sizes were inserted inside the breast. A treatment plan was delivered to the mobile and immobile phantom. The motion compensation accuracy was evaluated using three radiochromic films inserted inside the breast. Three dimensional conformal radiotherapy (3D-CRT), Tomotherapy (TOMO) and CK treatment plans were calculated for 10 consecutive patients who received APBI in Lille. To ensure a fair comparison of the three techniques, margins applied to the CTV were set to 10 mm. However, a second CK plan was prepared using 3 mm margins to evaluate the benefits of motion compensation. Only the larger clips (VITALITEC Medium-Large) could be tracked inside the larger breast (all gamma indices below 1 for 1 % of the maximum dose and 1 mm). All techniques meet the guidelines defined in the NSABP/RTOG and SHARE protocols. As the applied dose volume constraints are very strong, insignificant dosimetric differences exist between techniques regarding the PTV
International Nuclear Information System (INIS)
Rault, Erwann; Lacornerie, Thomas; Dang, Hong-Phuong; Crop, Frederik; Lartigau, Eric; Reynaert, Nick; Pasquier, David
2016-01-01
Accelerated partial breast irradiation (APBI) is a new breast treatment modality aiming to reduce treatment time using hypo fractionation. Compared to conventional whole breast irradiation that takes 5 to 6 weeks, APBI is reported to induce worse cosmetic outcomes both when using three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). These late normal tissue effects may be attributed to the dose volume effect because a large portion of the non-target breast tissue volume (NTBTV) receives a high dose. In the context of APBI, non-coplanar beams could spare the NTBTV more efficiently. This study evaluates the dosimetric benefit of using the Cyberknife (CK) for APBI in comparison to IMRT (Tomotherapy) and three dimensional conformal radiotherapy (3D-CRT). The possibility of using surgical clips, implanted during surgery, to track target movements is investigated first. A phantom of a female thorax was designed in-house using the measurements of 20 patients. Surgical clips of different sizes were inserted inside the breast. A treatment plan was delivered to the mobile and immobile phantom. The motion compensation accuracy was evaluated using three radiochromic films inserted inside the breast. Three dimensional conformal radiotherapy (3D-CRT), Tomotherapy (TOMO) and CK treatment plans were calculated for 10 consecutive patients who received APBI in Lille. To ensure a fair comparison of the three techniques, margins applied to the CTV were set to 10 mm. However, a second CK plan was prepared using 3 mm margins to evaluate the benefits of motion compensation. Only the larger clips (VITALITEC Medium-Large) could be tracked inside the larger breast (all gamma indices below 1 for 1 % of the maximum dose and 1 mm). All techniques meet the guidelines defined in the NSABP/RTOG and SHARE protocols. As the applied dose volume constraints are very strong, insignificant dosimetric differences exist between techniques regarding the PTV
Thermodynamics of de Sitter black holes with a conformally coupled scalar field
International Nuclear Information System (INIS)
Barlow, Anne-Marie; Doherty, Daniel; Winstanley, Elizabeth
2005-01-01
We study the thermodynamics of de Sitter black holes with a conformally coupled scalar field. The geometry is that of the lukewarm Reissner-Nordstroem-de Sitter black holes, with the event and cosmological horizons at the same temperature. This means that the region between the event and cosmological horizons can form a regular Euclidean instanton. The entropy is modified by the nonminimal coupling of the scalar field to the geometry, but can still be derived from the Euclidean action, provided suitable modifications are made to deal with the electrically charged case. We use the first law as derived from the isolated horizons formalism to compute the local horizon energies for the event and cosmological horizons
From here to criticality: Renormalization group flow between two conformal field theories
International Nuclear Information System (INIS)
Leaf-Herrmann, W.A.
1993-01-01
Using non-perturbative techniques, we study the renormalization group trajectory between two conformal field theories. Specifically, we investigate a perturbation of the A 3 superconformal minimal model such that in the infrared limit the theory flows to the A 2 model. The correlation functions in the topological sector of the theory are computed numerically along the trajectory, and these results are compared to the expected asymptotic behavior. Excellent agreement is found, and the characteristic features of the infrared theory, including the central charge and the normalized operator product expansion coefficients, are obtained. We also review and discuss some aspects of the geometrical description of N=2 supersymmetric quantum field theories recently uncovered by Cecotti and Vafa. (orig.)
Truncated conformal space approach to scaling Lee-Yang model
International Nuclear Information System (INIS)
Yurov, V.P.; Zamolodchikov, Al.B.
1989-01-01
A numerical approach to 2D relativstic field theories is suggested. Considering a field theory model as an ultraviolet conformal field theory perturbed by suitable relevant scalar operator one studies it in finite volume (on a circle). The perturbed Hamiltonian acts in the conformal field theory space of states and its matrix elements can be extracted from the conformal field theory. Truncation of the space at reasonable level results in a finite dimensional problem for numerical analyses. The nonunitary field theory with the ultraviolet region controlled by the minimal conformal theory μ(2/5) is studied in detail. 9 refs.; 17 figs
Low-dimensional filiform Lie algebras over finite fields
Falcón Ganfornina, Óscar Jesús; Núñez Valdés, Juan; Pacheco Martínez, Ana María; Villar Liñán, María Trinidad; Vasek, Vladimir (Coordinador); Shmaliy, Yuriy S. (Coordinador); Trcek, Denis (Coordinador); Kobayashi, Nobuhiko P. (Coordinador); Choras, Ryszard S. (Coordinador); Klos, Zbigniew (Coordinador)
2011-01-01
In this paper we use some objects of Graph Theory to classify low-dimensional filiform Lie algebras over finite fields. The idea lies in the representation of each Lie algebra by a certain type of graphs. Then, some properties on Graph Theory make easier to classify the algebras. As results, which can be applied in several branches of Physics or Engineering, for instance, we find out that there exist, up to isomorphism, six 6-dimensional filiform Lie algebras over Z/pZ, for p = 2, 3, 5. Pl...
Lattice formulation of a two-dimensional topological field theory
International Nuclear Information System (INIS)
Ohta, Kazutoshi; Takimi, Tomohisa
2007-01-01
We investigate an integrable property and the observables of 2-dimensional N=(4,4) topological field theory defined on a discrete lattice by using the 'orbifolding' and 'deconstruction' methods. We show that our lattice model is integrable and, for this reason, the partition function reduces to matrix integrals of scalar fields on the lattice sites. We elucidate meaningful differences between a discrete lattice and a differentiable manifold. This is important for studying topological quantities on a lattice. We also propose a new construction of N=(2,2) supersymmetric lattice theory, which is realized through a suitable truncation of scalar fields from the N=(4,4) theory. (author)
International Nuclear Information System (INIS)
Correa Pablos, Tamara; Caceres Toledo, Maria
2009-01-01
The eye and orbit metastases are a significant clinical problem, both by the inability and the deterioration in the quality of life that occur. The most common malignant tumors in the eye and orbit is metastasis. Cancer breast cancer is the most common tumor metastatic to the eye and orbit in a 40% and 50% of cases according to different series. With the introduction of Three-Dimensional Conformal Radiotherapy (3D-CRT) in our hospital from In 2007 we were able to treat patients with cancer different regions with the technique (2D) was impossible because caused irreparable damage to surrounding healthy tissue in this way thanks to potential of 3D technology to shape the planning volume will ensure greater protection for critical organs. (Author)
Statistical properties of nonlinear one-dimensional wave fields
Directory of Open Access Journals (Sweden)
D. Chalikov
2005-01-01
Full Text Available A numerical model for long-term simulation of gravity surface waves is described. The model is designed as a component of a coupled Wave Boundary Layer/Sea Waves model, for investigation of small-scale dynamic and thermodynamic interactions between the ocean and atmosphere. Statistical properties of nonlinear wave fields are investigated on a basis of direct hydrodynamical modeling of 1-D potential periodic surface waves. The method is based on a nonstationary conformal surface-following coordinate transformation; this approach reduces the principal equations of potential waves to two simple evolutionary equations for the elevation and the velocity potential on the surface. The numerical scheme is based on a Fourier transform method. High accuracy was confirmed by validation of the nonstationary model against known solutions, and by comparison between the results obtained with different resolutions in the horizontal. The scheme allows reproduction of the propagation of steep Stokes waves for thousands of periods with very high accuracy. The method here developed is applied to simulation of the evolution of wave fields with large number of modes for many periods of dominant waves. The statistical characteristics of nonlinear wave fields for waves of different steepness were investigated: spectra, curtosis and skewness, dispersion relation, life time. The prime result is that wave field may be presented as a superposition of linear waves is valid only for small amplitudes. It is shown as well, that nonlinear wave fields are rather a superposition of Stokes waves not linear waves. Potential flow, free surface, conformal mapping, numerical modeling of waves, gravity waves, Stokes waves, breaking waves, freak waves, wind-wave interaction.
Statistical properties of nonlinear one-dimensional wave fields
Chalikov, D.
2005-06-01
A numerical model for long-term simulation of gravity surface waves is described. The model is designed as a component of a coupled Wave Boundary Layer/Sea Waves model, for investigation of small-scale dynamic and thermodynamic interactions between the ocean and atmosphere. Statistical properties of nonlinear wave fields are investigated on a basis of direct hydrodynamical modeling of 1-D potential periodic surface waves. The method is based on a nonstationary conformal surface-following coordinate transformation; this approach reduces the principal equations of potential waves to two simple evolutionary equations for the elevation and the velocity potential on the surface. The numerical scheme is based on a Fourier transform method. High accuracy was confirmed by validation of the nonstationary model against known solutions, and by comparison between the results obtained with different resolutions in the horizontal. The scheme allows reproduction of the propagation of steep Stokes waves for thousands of periods with very high accuracy. The method here developed is applied to simulation of the evolution of wave fields with large number of modes for many periods of dominant waves. The statistical characteristics of nonlinear wave fields for waves of different steepness were investigated: spectra, curtosis and skewness, dispersion relation, life time. The prime result is that wave field may be presented as a superposition of linear waves is valid only for small amplitudes. It is shown as well, that nonlinear wave fields are rather a superposition of Stokes waves not linear waves. Potential flow, free surface, conformal mapping, numerical modeling of waves, gravity waves, Stokes waves, breaking waves, freak waves, wind-wave interaction.
International Nuclear Information System (INIS)
Song, Paul Y.; Washington, Maxine; Vaida, Florin; Hamilton, Russell; Spelbring, Danny; Wyman, Brenda; Harrison, Joanne; Chen, George T. Y.; Vijayakumar, Srinivasan
1996-01-01
Purpose: To determine the variability of patient positioning during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer treated with no immobilization or one of four immobilization devices, and to determine the effects of patient body habitus and pelvic circumference on patient movement with each individual immobilization technique. Methods and Materials: To see whether our immobilization techniques have improved day-to-day patient movement, a retrospective analysis was carried out. A total of 62 patients treated at one facility on a single machine with 3D-CRT via a four-field box technique (anterior-posterior and opposed laterals) in the supine position with either no immobilization or one of four immobilization devices. Five groups of patients were compared: (a) group 1-no immobilization; (b) group 2-alpha cradle from the waist to upper thigh; (c) group 3-alpha cradle from waist to below the knees; (d) group 4-styrofoam leg immobilizer (below knees); and (e) group 5-aquaplast cast encompassing the entire abdomen and pelvis to midthigh with alpha cradle immobilization to their lower legs and feet. Prior to starting radiotherapy, portal films of all four treatment fields were obtained 1 day before treatment. Subsequently, portal films were then obtained at least once a week. Portal films were compared with the simulation films and appropriate changes were made and verified on the next day prior to treatment. A deviation of greater than 0.5 cm or greater was considered to be clinically significant in our analysis. We studied the difference among the types of immobilization and no immobilization by looking at the frequency of movements (overall, and on each of the three axes) that a patient had during the course of his treatment. Using a logistic regression model, the probability of overall and individual directional movement for each group was obtained. In addition, the effects of patient body habitus and pelvic circumference on movement were
Hirata, Kimiko; Yoshimura, Michio; Mukumoto, Nobutaka; Nakamura, Mitsuhiro; Inoue, Minoru; Sasaki, Makoto; Fujimoto, Takahiro; Yano, Shinsuke; Nakata, Manabu; Mizowaki, Takashi; Hiraoka, Masahiro
2017-07-01
We evaluated three-dimensional intrafractional target motion, divided into respiratory-induced motion and baseline drift, in accelerated partial breast irradiation (APBI). Paired fluoroscopic images were acquired simultaneously using orthogonal kV X-ray imaging systems at pre- and post-treatment for 23 patients who underwent APBI with external beam radiotherapy. The internal target motion was calculated from the surgical clips placed around the tumour cavity. The peak-to-peak respiratory-induced motions ranged from 0.6 to 1.5mm in all directions. A systematic baseline drift of 1.5mm towards the posterior direction and a random baseline drift of 0.3mm in the lateral-medial and cranial-caudal directions were observed. The baseline for an outer tumour cavity drifted towards the lateral and posterior directions, and that for an upper tumour cavity drifted towards the cranial direction. Moderate correlations were observed between the posterior baseline drift and the patients' physical characteristics. The posterior margin for intrafractional uncertainties was larger than 5mm in patients with greater fat thickness due to the baseline drift. The magnitude of the intrafractional motion was not uniform according to the direction, patients' physical characteristics, or tumour cavity location due to the baseline drift. Therefore, the intrafractional systematic movement should be properly managed. Copyright © 2017 Elsevier B.V. All rights reserved.
Guilarte, Juan Mateos; Plyushchay, Mikhail S.
2017-12-01
We investigate a special class of the PT -symmetric quantum models being perfectly invisible zero-gap systems with a unique bound state at the very edge of continuous spectrum of scattering states. The family includes the PT -regularized two particle Calogero systems (conformal quantum mechanics models of de Alfaro-Fubini-Furlan) and their rational extensions whose potentials satisfy equations of the KdV hierarchy and exhibit, particularly, a behaviour typical for extreme waves. We show that the two simplest Hamiltonians from the Calogero subfamily determine the fluctuation spectra around the PT -regularized kinks arising as traveling waves in the field-theoretical Liouville and SU(3) conformal Toda systems. Peculiar properties of the quantum systems are reflected in the associated exotic nonlinear supersymmetry in the unbroken or partially broken phases. The conventional N=2 supersymmetry is extended here to the N=4 nonlinear supersymmetry that involves two bosonic generators composed from Lax-Novikov integrals of the subsystems, one of which is the central charge of the superalgebra. Jordan states are shown to play an essential role in the construction.
Improvement of Dose Homogeneity in a 3-Dimensional Conformal Radiotherapy for Head and Neck Cancer
International Nuclear Information System (INIS)
Kim, Yong Nam; Lee, Chang Geol; Chung, Kyeong Keun; Kim, Joo Young; Seong, Jin Sil
2007-01-01
When an electron field is abutted at the surface with a photon field for head-and-neck cancer (HNC) treatment, the traditional method using bilateral field gives rise to an extreme inhomogeneity of dose distribution with both very hot and very cold regions. When we consider clinically only tumor doses of primary concern regardless of dose to normal tissues, the hot spots can be accepted, depending on their magnitude, extent, and location. However, an extreme inhomogeneity inside the radiation field is generally undesirable. An overdose to normal tissues around a target region or an underdosage in the tumor may be problematic. This study intends to develop a novel approach to improve the dose distribution inside the photon-electron abutting fields for HNC treatment
N=2 Minimal Conformal Field Theories and Matrix Bifactorisations of x d
Davydov, Alexei; Camacho, Ana Ros; Runkel, Ingo
2018-01-01
We establish an action of the representations of N = 2-superconformal symmetry on the category of matrix factorisations of the potentials x d and x d - y d , for d odd. More precisely we prove a tensor equivalence between (a) the category of Neveu-Schwarz-type representations of the N = 2 minimal super vertex operator algebra at central charge 3-6/d, and (b) a full subcategory of graded matrix factorisations of the potential x d - y d . The subcategory in (b) is given by permutation-type matrix factorisations with consecutive index sets. The physical motivation for this result is the Landau-Ginzburg/conformal field theory correspondence, where it amounts to the equivalence of a subset of defects on both sides of the correspondence. Our work builds on results by Brunner and Roggenkamp [BR], where an isomorphism of fusion rules was established.
Bulk Renormalization Group Flows and Boundary States in Conformal Field Theories
Directory of Open Access Journals (Sweden)
John Cardy
2017-08-01
Full Text Available We propose using smeared boundary states $e^{-\\tau H}|\\cal B\\rangle$ as variational approximations to the ground state of a conformal field theory deformed by relevant bulk operators. This is motivated by recent studies of quantum quenches in CFTs and of the entanglement spectrum in massive theories. It gives a simple criterion for choosing which boundary state should correspond to which combination of bulk operators, and leads to a rudimentary phase diagram of the theory in the vicinity of the RG fixed point corresponding to the CFT, as well as rigorous upper bounds on the universal amplitude of the free energy. In the case of the 2d minimal models explicit formulae are available. As a side result we show that the matrix elements of bulk operators between smeared Ishibashi states are simply given by the fusion rules of the CFT.
Conformal field theory construction for non-Abelian hierarchy wave functions
Tournois, Yoran; Hermanns, Maria
2017-12-01
The fractional quantum Hall effect is the paradigmatic example of topologically ordered phases. One of its most fascinating aspects is the large variety of different topological orders that may be realized, in particular non-Abelian ones. Here we analyze a class of non-Abelian fractional quantum Hall model states which are generalizations of the Abelian Haldane-Halperin hierarchy. We derive their topological properties and show that the quasiparticles obey non-Abelian fusion rules of type su (q)k . For a subset of these states we are able to derive the conformal field theory description that makes the topological properties—in particular braiding—of the state manifest. The model states we study provide explicit wave functions for a large variety of interesting topological orders, which may be relevant for certain fractional quantum Hall states observed in the first excited Landau level.
International Nuclear Information System (INIS)
Ge, Xiao-hui; Liu, Miao-ling; Lin, Qiang; Ren, Xiao-cang; Liu, Yue-e; Chen, Xue-ji; Wang, Dong-ying; Wang, Yong-qiang; Cao, Bin; Li, Zhi-gang
2013-01-01
Patients with brain metastases from lung cancer have poor prognoses and short survival time, and they are often excluded from clinical trials. Whole-cranial irradiation is considered to be the standard treatment, but its efficacy is not satisfactory. The purpose of this phase II clinical trial was to evaluate the preliminary efficacy and safety of the treatment of whole-brain irradiation plus three-dimensional conformal boost combined with concurrent topotecan for the patients with brain metastases from lung cancer. Patients with brain metastasis from lung cancer received concurrent chemotherapy and radiotherapy: conventional fractionated whole-brain irradiation, 2 fields/time, 1 fraction/day, 2 Gy/fraction, 5 times/week, and DT 40 Gy/20 fractions; for the patients with ≤ 3 lesions with diameter ≥ 2 cm, a three-dimensional (3-D) conformal localised boost was given to increase the dosage to 56–60 Gy; and during radiotherapy, concurrent chemotherapy with topotecan was given (the chemoradiotherapy group, CRT). The patients with brain metastasis from lung cancer during the same period who received radiotherapy only were selected as the controls (the radiotherapy-alone group, RT). From March 2009 to March 2012, both 38 patients were enrolled into two groups. The median progression-free survival(PFS) time , the 1- and 2-year PFS rates of CRT group and RT group were 6 months, 42.8%, 21.6% and 3 months, 11.6%, 8.7% (χ 2 = 6.02, p = 0.014), respectively. The 1- and 2-year intracranial lesion control rates of CRT and RT were 75.9% , 65.2% and 41.6% , 31.2% (χ 2 = 3.892, p = 0.049), respectively. The 1- and 2-year overall survival rates (OS) of CRT and RT were 50.8% , 37.9% and 40.4% , 16.5% (χ 2 = 1.811, p = 0.178), respectively. The major side effects were myelosuppression and digestive toxicities, but no differences were observed between the two groups. Compared with radiotherapy alone, whole-brain irradiation plus 3-D conformal boost irradiation and concurrent
International Nuclear Information System (INIS)
Berthault, Patrick
1988-01-01
Oligosaccharides are natural compounds of huge importance as they intervene in all metabolic processes of cell life. Before the determination of structure-activity relationships, a precise knowledge of their chemical nature is therefore required. Thus, this research thesis aims at describing various experiments of high resolution nuclear magnetic resonance (NMR), and at demonstrating their applications on four oligosaccharides. After a brief description of NMR principles by using a conventional description and also a formalism derived from quantum mechanics, the author outlines the weaknesses of old NMR techniques, and introduces new techniques by using scalar couplings, by processing magnetization transfers with one-dimensional hetero-nuclear experiments. General principles of two-dimensional experiments are then presented and developed in terms of simple correlations, multiple correlations, correlations via double quantum coherencies. Experiments with light water are then described, and different experiments are performed to determine the structure and conformation of each unit. Bipolar interactions are then addressed to highlight proximities between atoms [fr
Topological field theories and two-dimensional instantons
International Nuclear Information System (INIS)
Schaposnik, F.A.
1990-01-01
In this paper, the author discusses some topics related to the recently developed Topological Field Theories (TFTs). The first part is devoted to a discussion on how a TFT can be quantized using techniques which are well-known from the study of gauge theories. Then the author describes the results that we have obtained in collaboration with George Thompson in the study of a two-dimensional TFT related to the Abelian Higgs model
Dimensional regularisation of Chern-Simons field theory
International Nuclear Information System (INIS)
Martin, C.P.
1990-01-01
We discuss the dimensional regularisation program as applied to a pure Chern-Simons theory in Minkowski space. In order to make this regularisation program feasible, we propose adding a Yang-Mills term to the pure Chern-Simons action. It is argued that the pure Chern-Simons theory is recovered in a certain limit. Explicit computations are carried out at the one-loop level in the background field gauge. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Ono, Junichi [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585 (Japan); Takada, Shoji [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585 (Japan); Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Saito, Shinji, E-mail: shinji@ims.ac.jp [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585 (Japan); The Graduate University for Advanced Studies, Okazaki 444-8585 (Japan)
2015-06-07
An analytical method based on a three-time correlation function and the corresponding two-dimensional (2D) lifetime spectrum is developed to elucidate the time-dependent couplings between the multi-timescale (i.e., hierarchical) conformational dynamics in heterogeneous systems such as proteins. In analogy with 2D NMR, IR, electronic, and fluorescence spectroscopies, the waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra can provide a quantitative description of the dynamical correlations between the conformational motions with different lifetimes. The present method is applied to intrinsic conformational changes of substrate-free adenylate kinase (AKE) using long-time coarse-grained molecular dynamics simulations. It is found that the hierarchical conformational dynamics arise from the intra-domain structural transitions among conformational substates of AKE by analyzing the one-time correlation functions and one-dimensional lifetime spectra for the donor-acceptor distances corresponding to single-molecule Förster resonance energy transfer experiments with the use of the principal component analysis. In addition, the complicated waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra for the donor-acceptor distances is attributed to the fact that the time evolution of the couplings between the conformational dynamics depends upon both the spatial and temporal characters of the system. The present method is expected to shed light on the biological relationship among the structure, dynamics, and function.
Wave field restoration using three-dimensional Fourier filtering method.
Kawasaki, T; Takai, Y; Ikuta, T; Shimizu, R
2001-11-01
A wave field restoration method in transmission electron microscopy (TEM) was mathematically derived based on a three-dimensional (3D) image formation theory. Wave field restoration using this method together with spherical aberration correction was experimentally confirmed in through-focus images of amorphous tungsten thin film, and the resolution of the reconstructed phase image was successfully improved from the Scherzer resolution limit to the information limit. In an application of this method to a crystalline sample, the surface structure of Au(110) was observed in a profile-imaging mode. The processed phase image showed quantitatively the atomic relaxation of the topmost layer.
Two dimensional topological insulator in quantizing magnetic fields
Olshanetsky, E. B.; Kvon, Z. D.; Gusev, G. M.; Mikhailov, N. N.; Dvoretsky, S. A.
2018-05-01
The effect of quantizing magnetic field on the electron transport is investigated in a two dimensional topological insulator (2D TI) based on a 8 nm (013) HgTe quantum well (QW). The local resistance behavior is indicative of a metal-insulator transition at B ≈ 6 T. On the whole the experimental data agrees with the theory according to which the helical edge states transport in a 2D TI persists from zero up to a critical magnetic field Bc after which a gap opens up in the 2D TI spectrum.
Three-dimensional phase-field simulations of directional solidification
Plapp, Mathis
2007-05-01
The phase-field method has become the method of choice for simulating microstructural pattern formation during solidification. One of its main advantages is that time-dependent three-dimensional simulations become feasible, which makes it possible to address long-standing questions of pattern stability and pattern selection. Here, a brief introduction to the phase-field model and its implementation is given, and its capabilities are illustrated by examples taken from the directional solidification of binary alloys. In particular, the morphological stability of hexagonal cellular arrays and of eutectic lamellar patterns is investigated.
Czech Academy of Sciences Publication Activity Database
Vránová, J.; Vinakurau, S.; Richter, J.; Starec, M.; Fišerová, Anna; Rosina, J.
2011-01-01
Roč. 2, č. 6 (2011), s. 1-13 ISSN 1748-717X R&D Projects: GA AV ČR IAA500200620 Institutional research plan: CEZ:AV0Z50200510 Keywords : 3-dimensional conformal radiotherapy (3DCRT) * gastrointestinal and genitourinary toxicity * prostate cancer Subject RIV: EC - Immunology Impact factor: 2.321, year: 2011
An Ar threesome: Matrix models, 2d conformal field theories, and 4dN=2 gauge theories
International Nuclear Information System (INIS)
Schiappa, Ricardo; Wyllard, Niclas
2010-01-01
We explore the connections between three classes of theories: A r quiver matrix models, d=2 conformal A r Toda field theories, and d=4N=2 supersymmetric conformal A r quiver gauge theories. In particular, we analyze the quiver matrix models recently introduced by Dijkgraaf and Vafa (unpublished) and make detailed comparisons with the corresponding quantities in the Toda field theories and the N=2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in order for them to reproduce the instanton partition functions in quiver gauge theories in five dimensions.
Energy Technology Data Exchange (ETDEWEB)
Pham, Daniel, E-mail: daniel.pham@petermac.org [Department of Radiotherapy Services, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Victoria (Australia); Thompson, Ann [Department of Radiotherapy Services, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Kron, Tomas [Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne, Victoria (Australia); Foroudi, Farshad [Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne, Victoria (Australia); Department of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Kolsky, Michal Schneider [Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Victoria (Australia); Devereux, Thomas; Lim, Andrew [Department of Radiotherapy Services, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Siva, Shankar [Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne, Victoria (Australia); Department of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia)
2014-12-01
Purpose: To describe our 3-dimensional conformal planning approaches and report early toxicities with stereotactic body radiation therapy for the management of primary renal cell carcinoma. Methods and Materials: This is an analysis of a phase 1 trial of stereotactic body radiation therapy for primary inoperable renal cell carcinoma. A dose of 42 Gy/3 fractions was prescribed to targets ≥5 cm, whereas for <5 cm 26 Gy/1 fraction was used. All patients underwent a planning 4-dimensional CT to generate a planning target volume (PTV) from a 5-mm isotropic expansion of the internal target volume. Planning required a minimum of 8 fields prescribing to the minimum isodose surrounding the PTV. Intermediate dose spillage at 50% of the prescription dose (R50%) was measured to describe the dose gradient. Early toxicity (<6 months) was scored using the Common Terminology Criteria for Adverse Events (v4.0). Results: From July 2012 to August 2013 a total of 20 patients (median age, 77 years) were recruited into a prospective clinical trial. Eleven patients underwent fractionated treatment and 9 patients a single fraction. For PTV targets <100 cm{sup 3} the median number of beams used was 8 (2 noncoplanar) to achieve an average R50% of 3.7. For PTV targets >100 cm{sup 3} the median beam number used was 10 (4 noncoplanar) for an average R50% value of 4.3. The R50% was inversely proportional to decreasing PTV volume (r=−0.62, P=.003) and increasing total beams used (r=−0.51, P=.022). Twelve of 20 patients (60%) suffered grade ≤2 early toxicity, whereas 8 of 20 patients (40%) were asymptomatic. Nausea, chest wall pain, and fatigue were the most common toxicities reported. Conclusion: A 3-dimensional conformal planning technique of 8-10 beams can be used to deliver highly tolerable stereotactic ablation to primary kidney targets with minimal early toxicities. Ongoing follow-up is currently in place to assess long-term toxicities and cancer control.
Functional representations for quantized fields
International Nuclear Information System (INIS)
Jackiw, R.
1988-01-01
This paper provides information on Representing transformations in quantum theory bosonic quantum field theories: Schrodinger Picture; Represnting Transformations in Bosonic Quantum Field Theory; Two-Dimensional Conformal Transformations, Schrodinger picture representation, Fock space representation, Inequivalent Schrodinger picture representations; Discussion, Self-Dual and Other Models; Field Theory in de Sitter Space. Fermionic Quantum Field Theories: Schroedinger Picture; Schrodinger Picture Representation for Two-Dimensional; Conformal Transformations; Fock Space Dynamics in the Schrodinger Picture; Fock Space Evaluation of Anomalous Current and Conformal Commutators
Conformal symmetry and string theories
International Nuclear Information System (INIS)
Kumar, A.
1987-01-01
This thesis is devoted to the study of various aspects of the 2-dimensional conformal field theory and its applications to strings. We make a short review of the conformal field theory and its supersymmetric extension, called superconformal field theory. We present an elegant superspace formulation of these theories and solve the condition for the closure of the superconformal algebra. The we go on to classify the superconformal field theories according to these solutions. We prove that N ≥ 5 superconformal algebra, with N being the number of supersymmetries, does not have central charge. We find the primary representations of all the interesting superconformal algebra. We study the quantization of the superconformal theories and derive the constraints on the central charge of the algebra that has to be satisfied for a consistent quantum theory. This quantization process also determines the ground state energy of the system and the spectrum of the model. We study the global aspects of the conformal symmetry and its role in the construction of consistent heterotic string theories. We prove the uniqueness of heterotic superstring theories in 10 dimensions in the fermionic constructions. We show how the vertex operators are closely associated with the primary field representation of the conformal algebra. We utilize these vertex operator constructions to obtain tree amplitudes in the 10-dimensional heterotic string theory. We show by explicit calculation at the 3-point level that the scattering amplitudes derived from the heterotic superstring are same as the ones obtained from 10-dimensional supergravity theories
Geometrical formulation of the conformal Ward identity
International Nuclear Information System (INIS)
Kachkachi, M.
2002-08-01
In this paper we use deep ideas in complex geometry that proved to be very powerful in unveiling the Polyakov measure on the moduli space of Riemann surfaces and lead to obtain the partition function of perturbative string theory for 2, 3, 4 loops. Indeed, a geometrical interpretation of the conformal Ward identity in two dimensional conformal field theory is proposed: the conformal anomaly is interpreted as a deformation of the complex structure of the basic Riemann surface. This point of view is in line with the modern trend of geometric quantizations that are based on deformations of classical structures. Then, we solve the conformal Ward identity by using this geometrical formalism. (author)
Mani, Karthick Raj; Basu, Saumen; Bhuiyan, Md Anisuzzaman; Ahmed, Sharif; Sumon, Mostafa Aziz; Haque, Kh Anamul; Sengupta, Ashim Kumar; Un Nabi, Md Rashid; Das, K. J. Maria
2017-06-01
Objective: The purpose of this study is to demonstrate the synchronous bilateral breast irradiation radiotherapy technique using a single isocenter. Materials and Methods: Six patients of synchronous bilateral breast were treated with single isocenter technique from February 2011 to June 2016. All the patients underwent a CT-simulation using appropriate positioning device. Target volumes and critical structures like heart, lung, esophagus, thyroid, etc., were delineated slice by slice in the CT data. An isocenter was placed above the sternum on the skin and both medial tangential and lateral tangential of the breast / chest wall were created using asymmetrical jaws to avoid the beam divergence through the lung and heart. The field weighting were adjusted manually to obtain a homogenous dose distribution. The planning objectives were to deliver uniform doses around the target and keep the doses to the organ at risk within the permissible limit. The beam energy of 6 MV or combination of 6 MV and 15 MV photons were used in the tangential fields according to the tangential separation. Boluses were used for all the mastectomy patients to increase the doses on the chest wall. In addition to that enhanced dynamic wedge and field in field technique were also used to obtain a homogenous distribution around the target volume and reduce the hot spots. The isocenter was just kept on the skin, such that the beam junctions will be overlapped only on the air just above the sternum. Acute toxicity during the treatment and late toxicity were recorded during the patient's follow-up. Results: During the radiotherapy treatment follow-up there were no acute skin reactions in the field junctions, but one patient had grade 1 esophagitis and two patients had grade 2 skin reactions in the chest wall. With a median follow-up of 38.5 months (range: 8 - 49 months), no patients had a local recurrence, but one patients with triple negative disease had a distant metastases in brain and died
Conformal invariance at a deconfinement phase transition in (2+1) dimensions
International Nuclear Information System (INIS)
Christensen, J.; Damgaard, P.H.
1990-08-01
The conformal dimension of the Polyakov line at the deconfinement phase transition of (2+1)-dimensional SU(2) lattice gauge theory is determined numerically using two-dimensional finite size conformal field theory. Excellent agreement with two-dimensional Ising model values is found for both the renormalized coupling on a spatially toroidal geometry and the conformal dimensions on a finite-width strip geometry. (orig.)
Tian, Mei-ling; Fang, Ting; Du, Mu-ying; Zhang, Fu-sheng
2016-04-01
To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of α-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of α-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 ± 1.14% compared with control. The activation effect could last for 18 h at 4 °C. PEF treatment could widen the range of optimum temperature for α-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, α-amylase treated by PEF showed an increase of Vmax, t1/2 and ΔG, whereas a decrease of Km and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on α-amylase surface with enhanced α-helices by 34.76% and decreased random coil by 12.04% on α-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing α-amylase activity and property.
International Nuclear Information System (INIS)
Galland-Girodet, Sigolène; Pashtan, Itai; MacDonald, Shannon M.; Ancukiewicz, Marek; Hirsch, Ariel E.; Kachnic, Lisa A.; Specht, Michelle; Gadd, Michele; Smith, Barbara L.; Powell, Simon N.; Recht, Abram; Taghian, Alphonse G.
2014-01-01
Purpose: To present long-term outcomes of a prospective feasibility trial using either protons or 3-dimensional conformal photon-based (accelerated partial-breast irradiation [APBI]) techniques. Methods and Materials: From October 2003 to April 2006, 98 evaluable patients with stage I breast cancer were treated with APBI (32 Gy in 8 fractions given twice daily) on a prospective clinical trial: 19 with proton beam therapy (PBT) and 79 with photons or mixed photons/electrons. Median follow-up was 82.5 months (range, 2-104 months). Toxicity and patient satisfaction evaluations were performed at each visit. Results: At 7 years, the physician rating of overall cosmesis was good or excellent for 62% of PBT patients, compared with 94% for photon patients (P=.03). Skin toxicities were more common for the PBT group: telangiectasia, 69% and 16% (P=.0013); pigmentation changes, 54% and 22% (P=.02); and other late skin toxicities, 62% and 18% (P=.029) for PBT and photons, respectively. There were no significant differences between the groups in the incidences of breast pain, edema, fibrosis, fat necrosis, skin desquamation, and rib pain or fracture. Patient-reported cosmetic outcomes at 7 years were good or excellent for 92% and 96% of PBT and photon patients, respectively (P=.95). Overall patient satisfaction was 93% for the entire cohort. The 7-year local failure rate for all patients was 6%, with 3 local recurrences in the PBT group (7-year rate, 11%) and 2 in photon-treated patients (4%) (P=.22). Conclusions: Local failure rates of 3-dimensional APBI and PBT were similar in this study. However, PBT, as delivered in this study, led to higher rates of long-term telangiectasia, skin color changes, and skin toxicities. We recommend the use of multiple fields and treatment of all fields per treatment session or the use of scanning techniques to minimize skin toxicity
Energy Technology Data Exchange (ETDEWEB)
Galland-Girodet, Sigolène; Pashtan, Itai; MacDonald, Shannon M.; Ancukiewicz, Marek [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Hirsch, Ariel E.; Kachnic, Lisa A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts (United States); Specht, Michelle; Gadd, Michele; Smith, Barbara L. [Department of Surgical Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Powell, Simon N. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Recht, Abram [Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts (United States); Taghian, Alphonse G., E-mail: ataghian@partners.org [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States)
2014-11-01
Purpose: To present long-term outcomes of a prospective feasibility trial using either protons or 3-dimensional conformal photon-based (accelerated partial-breast irradiation [APBI]) techniques. Methods and Materials: From October 2003 to April 2006, 98 evaluable patients with stage I breast cancer were treated with APBI (32 Gy in 8 fractions given twice daily) on a prospective clinical trial: 19 with proton beam therapy (PBT) and 79 with photons or mixed photons/electrons. Median follow-up was 82.5 months (range, 2-104 months). Toxicity and patient satisfaction evaluations were performed at each visit. Results: At 7 years, the physician rating of overall cosmesis was good or excellent for 62% of PBT patients, compared with 94% for photon patients (P=.03). Skin toxicities were more common for the PBT group: telangiectasia, 69% and 16% (P=.0013); pigmentation changes, 54% and 22% (P=.02); and other late skin toxicities, 62% and 18% (P=.029) for PBT and photons, respectively. There were no significant differences between the groups in the incidences of breast pain, edema, fibrosis, fat necrosis, skin desquamation, and rib pain or fracture. Patient-reported cosmetic outcomes at 7 years were good or excellent for 92% and 96% of PBT and photon patients, respectively (P=.95). Overall patient satisfaction was 93% for the entire cohort. The 7-year local failure rate for all patients was 6%, with 3 local recurrences in the PBT group (7-year rate, 11%) and 2 in photon-treated patients (4%) (P=.22). Conclusions: Local failure rates of 3-dimensional APBI and PBT were similar in this study. However, PBT, as delivered in this study, led to higher rates of long-term telangiectasia, skin color changes, and skin toxicities. We recommend the use of multiple fields and treatment of all fields per treatment session or the use of scanning techniques to minimize skin toxicity.
Two dimensional analytical model for a reconfigurable field effect transistor
Ranjith, R.; Jayachandran, Remya; Suja, K. J.; Komaragiri, Rama S.
2018-02-01
This paper presents two-dimensional potential and current models for a reconfigurable field effect transistor (RFET). Two potential models which describe subthreshold and above-threshold channel potentials are developed by solving two-dimensional (2D) Poisson's equation. In the first potential model, 2D Poisson's equation is solved by considering constant/zero charge density in the channel region of the device to get the subthreshold potential characteristics. In the second model, accumulation charge density is considered to get above-threshold potential characteristics of the device. The proposed models are applicable for the device having lightly doped or intrinsic channel. While obtaining the mathematical model, whole body area is divided into two regions: gated region and un-gated region. The analytical models are compared with technology computer-aided design (TCAD) simulation results and are in complete agreement for different lengths of the gated regions as well as at various supply voltage levels.
Field theories on conformally related space-times: Some global considerations
International Nuclear Information System (INIS)
Candelas, P.; Dowker, J.S.
1979-01-01
The nature of the vacua appearing in the relation between the vacuum expectation value of stress tensors in conformally flat spaces is clarified. The simple but essential point is that the relevant spaces should have conformally related global Cauchy surfaces. Some commonly occurring conformally flat space-times are divided into two families according to whether they are conformally equivalent to Minkowski space or to the Rindler wedge. Expressions, some new, are obtained for the vacuum expectation value of the stress tensor for a number of illustrative cases. It is noted that thermalization relates the Green's functions of these two families
Discussion of the duality in three dimensional quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Ma, Chen-Te, E-mail: yefgst@gmail.com
2017-05-10
We discuss the duality in three dimensional quantum field theory at infrared limit. The starting point is to use a conjecture of a duality between the free fermion and the interacting scalar field theories at the Wilson–Fisher fixed point. The conjecture is useful for deriving various dualities in three dimensions to obtain a duality web. The study is also interesting for understanding the dualities, or equivalence of different theories from the perspective of the renormalization group flow. We first discuss the “derivation” without losing the holonomy. Furthermore, we also derive these dualities from the mean-field study, and consider the extension of the conjecture or dualities at finite temperature.
International Nuclear Information System (INIS)
Ercan, T.; Alco, G.; Zengin, F.; Atilla, S.; Dincer, M.; Igdem, S.; Okkan, S.
2010-01-01
The aim of this study was to be able to implement the field-in-field intensity-modulated radiotherapy (FiF) technique in our daily practice for breast radiotherapy. To do this, we performed a dosimetric comparison. Treatment plans were produced for 20 consecutive patients. FiF plans and conformal radiotherapy (CRT) plans were compared for doses in the planning target volume (PTV), the dose homogeneity index (DHI), doses in irradiated soft tissue outside the target volume (SST), ipsilateral lung and heart doses for left breast irradiation, and the monitor unit counts (MU) required for treatment. Averaged values were compared using Student's t-test. With FiF, the DHI is improved 7.0% and 5.7%, respectively (P<0.0001) over the bilateral and lateral wedge CRT techniques. When the targeted volumes received 105% and 110% of the prescribed dose in the PTV were compared, significant decreases are found with the FiF technique. With the 105% dose, the SST, heart, and ipsilateral lung doses and the MU counts were also significantly lower with the FiF technique. The FiF technique, compared to CRT, for breast radiotherapy enables significantly better dose distribution in the PTV. Significant differences are also found for soft tissue volume, the ipsilateral lung dose, and the heart dose. Considering the decreased MUs needed for treatment, the FiF technique is preferred over tangential CRT. (author)
Degenerate conformal theories on higher-genus surfaces
International Nuclear Information System (INIS)
Gerasimov, A.A.
1989-01-01
Two-dimensional degenerate field theories on higher-genus surfaces are investigated. Objects are built on the space of moduli, whose linear combinations are hypothetically conformal blocks in degenerate theories
Araneda, Bernardo
2018-04-01
We present weighted covariant derivatives and wave operators for perturbations of certain algebraically special Einstein spacetimes in arbitrary dimensions, under which the Teukolsky and related equations become weighted wave equations. We show that the higher dimensional generalization of the principal null directions are weighted conformal Killing vectors with respect to the modified covariant derivative. We also introduce a modified Laplace–de Rham-like operator acting on tensor-valued differential forms, and show that the wave-like equations are, at the linear level, appropriate projections off shell of this operator acting on the curvature tensor; the projection tensors being made out of weighted conformal Killing–Yano tensors. We give off shell operator identities that map the Einstein and Maxwell equations into weighted scalar equations, and using adjoint operators we construct solutions of the original field equations in a compact form from solutions of the wave-like equations. We study the extreme and zero boost weight cases; extreme boost corresponding to perturbations of Kundt spacetimes (which includes near horizon geometries of extreme black holes), and zero boost to static black holes in arbitrary dimensions. In 4D our results apply to Einstein spacetimes of Petrov type D and make use of weighted Killing spinors.
Directory of Open Access Journals (Sweden)
Daniel Caterbow
2011-07-01
Full Text Available The position of the peripheral nitrogen atoms in bis(terpyridine-derived oligopyridines (BTPs has a strong impact on their self-assembly behavior at the liquid/HOPG (highly oriented pyrolytic graphite interface. The intermolecular hydrogen bonding interactions in these peripheral pyridine units show specific 2D structures for each BTP isomer. From nine possible constitutional isomers only four have been described in the literature. The synthesis and self-assembling behavior of an additional isomer is presented here, but the remaining four members of the series are synthetically inaccessible. The self-assembling properties of three of the missing four BTP isomers can be mimicked by making use of the energetically preferred N–C–C–N transoid conformation between 2,2'-bipyridine subunits in a new class of so-called septipyridines. The structures are investigated by scanning tunneling microscopy (STM and a combination of force-field and first-principles electronic structure calculations.
Field analysis of two-dimensional focusing grating
Borsboom, P.P.; Frankena, H.J.
1995-01-01
The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal region has been determined for symmetrical chirped gratings consisting of as many as 124 corrugations. The intensity distribution in the focal region agrees well with the approximate predictions of geo...
Gommans, R.; Sandstrom, Marlene J.; Stevens, G.W.J.M.; ter Bogt, T.F.M.; Cillessen, Toon
2017-01-01
Adolescents tend to alter their attitudes and behaviors to match those of others; a peer influence process named peer conformity. This study investigated to what extent peer conformity depended on the status (popularity and likeability) of the influencer and the influencee. The study consisted of
International Nuclear Information System (INIS)
Morris, David E.; Emami, Bahman; Mauch, Peter M.; Konski, Andre A.; Tao, May L.; Ng, Andrea K.; Klein, Eric A.; Mohideen, Najeeb; Hurwitz, Mark D.; Fraas, Bendick A.; Roach, Mack; Gore, Elizabeth M.; Tepper, Joel E.
2005-01-01
Purpose: To perform a systematic review of the evidence to determine the efficacy and effectiveness of three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer; provide a clear presentation of the key clinical outcome questions related to the use of 3D-CRT in the treatment of localized prostate cancer that may be answered by a formal literature review; and provide concise information on whether 3D-CRT improves the clinical outcomes in the treatment of localized prostate cancer compared with conventional RT. Methods and Materials: We performed a systematic review of the literature through a structured process developed by the American Society for Therapeutic Radiology and Oncology's Outcomes Committee that involved the creation of a multidisciplinary task force, development of clinical outcome questions, a formal literature review and data abstraction, data review, and outside peer review. Results: Seven key clinical questions were identified. The results and task force conclusions of the literature review for each question are reported. Conclusion: The technological goals of reducing morbidity with 3D-CRT have been achieved. Randomized trials and follow-up of completed trials remain necessary to address these clinical outcomes specifically with regard to patient subsets and the use of hormonal therapy
International Nuclear Information System (INIS)
Arcangeli, Giorgio; Fowler, Jack; Gomellini, Sara; Arcangeli, Stefano; Saracino, Biancamaria; Petrongari, Maria Grazia; Benassi, Marcello; Strigari, Lidia
2011-01-01
Purpose: To compare the toxicity between hypofractionation vs. conventional fractionation schedules in patients with high-risk prostate cancer. Methods and Materials: Between January 2003 and December 2007, 168 patients were randomized to receive either hypofractionated (62 Gy in 20 fractions within 5 weeks, 4 fractions/wk) or conventionally fractionated (80 Gy in 40 fractions within 8 weeks) three-dimensional conformal radiotherapy to the prostate and seminal vesicles. All patients had undergone a 9-month course of total androgen deprivation, with radiotherapy starting 2 months after initiation of the total androgen deprivation. Results: The median follow-up was 32 and 35 months in the hypofractionation and conventional fractionation arms, respectively. For the patients developing acute toxicity, no difference between the two fractionation groups was found in either severity or duration of gastrointestinal or genitourinary toxicity. Also, no difference was found in the incidence and severity of late gastrointestinal and genitourinary toxicity between the two treatment schedules, with a 3-year rate of Grade 2 or greater toxicity of 17% and 16% for the hypofractionation arm and 14% and 11% for the conventional fractionation arm, respectively. A statistically significant correlation between acute and late gastrointestinal toxicity was found only in the conventional fractionation group. Conclusion: Our findings suggest that the hypofractionation regimen used in our study is safe, with only a slight, nonsignificant increase in tolerable and temporary acute toxicity compared with the conventional fractionation schedule. The severity and frequency of late complications was equivalent between the two treatment groups.
International Nuclear Information System (INIS)
Yu Jinming; Zheng Aiqing; Yu Yonghua; Wang Xuetao; Yuan Shuanghu; Han Dali; Li Kunhai
2005-01-01
Objective: To evaluate the effect and complication of non-small-cell lung cancer (NSCLC) treated with accelerated hypofractionated three dimensional conforms] radiation therapy (3DCRT). Methods: There were squamous carcinoma 21, adenocarcinoma 7, squamous-adenocarcinoma 4 and other cancer 3. There were 17 stage I and 18 stage II. Thirty-five patients of NSCLC were treated with a dose of 30-48 Gy in 6 or 8 Gy per fraction, 3 times a week. The outcome of these patients Was analyzed. Results: The overall 1-, 2- and 3- Year survival rate was 78.2%, 46.9% and 36.3%, respectively. The 1- and 2-year recurrence-free survival rate was 64.6 % and 39.7 %, respectively. The acute radiation pneumonitis and late lung fibrosis rates were high. Univariate analysis showed that Vm was a significant predictor of acute radiation pneumonitis. Conclusion: Compared with accelerated hypofractionated irradiation, the routine conventional fractionated radiation therapy may be preferred for more patients of NSCLC. (authors)
International Nuclear Information System (INIS)
Wielen, Gerard J. van der; Putten, Wim van; Incrocci, Luca
2007-01-01
Purpose: The purpose of this study is to provide information about sexual function (SF) after three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer while taking important factors into account that influence SF. Methods and Materials: Between June 1997 and February 2003, a total of 268 patients from a randomized dose-escalation trial comparing 68 Gy and 78 Gy agreed to participate in an additional part of the trial that evaluated SF. Results: At baseline 28% of patients had erectile dysfunction (ED). After 1 year, 27% of the pretreatment potent patients had developed ED. After 2 years this percentage had increased to 36%. After 3 years it almost stabilized at 38%. Satisfaction with sexual life was significantly correlated with ED. After 2 years one third of the pre-treatment potent patients still had considerable to very much sexual desire and found sex (very) important. No significant differences were found between the two dose-arms. Potency aids were used on a regular base by 14% of the patients. Conclusion: By taking adjuvant hormonal therapy (HT), HT during follow-up and potency aids into account, we found a lower percentage of ED after 3D-CRT than reported in previous prospective studies. A large group of patients still had sexual desire, considered sex important and 14% used potency aids after 3D-CRT
Directory of Open Access Journals (Sweden)
Ana Paula Diniz Fortuna Poli
2016-02-01
Full Text Available Abstract Objective: To evaluate the rectal volume influence on prostate motion during three-dimensional conformal radiotherapy (3D-CRT for prostate cancer. Materials and Methods: Fifty-one patients with prostate cancer underwent a series of three computed tomography scans including an initial planning scan and two subsequent scans during 3D-CRT. The organs of interest were outlined. The prostate contour was compared with the initial CT images considering the anterior, posterior, superior, inferior and lateral edges of the organ. Variations in the anterior limits and volume of the rectum were assessed and correlated with prostate motion in the anteroposterior direction. Results: The maximum range of prostate motion was observed in the superoinferior direction, followed by the anteroposterior direction. A significant correlation was observed between prostate motion and rectal volume variation ( p = 0.037. A baseline rectal volume superior to 70 cm3 had a significant influence on the prostate motion in the anteroposterior direction ( p = 0.045. Conclusion: The present study showed a significant interfraction motion of the prostate during 3D-CRT with greatest variations in the superoinferior and anteroposterior directions, and that a large rectal volume influences the prostate motion with a cutoff value of 70 cm3. Therefore, the treatment of patients with a rectal volume > 70 cm3 should be re-planned with appropriate rectal preparation.
Directory of Open Access Journals (Sweden)
Uğur Selek
2014-12-01
Full Text Available Chemoradiotherapy is the current standard of care in patients with advanced inoperable stage IIIA or IIIB non-small cell lung cancer (NSCLC. Three-dimensional radiotherapy (3DCRT has been a trusted method for a long time and has well-known drawbacks, most of which could be improved by Intensity Modulated Radiotherapy (IMRT. IMRT is not currently the standard treatment of locally advanced NSCLC, but almost all patients could benefit to a degree in organ at risk sparing, dose coverage conformality, or dose escalation. The most critical step for a radiation oncology department is to strictly evaluate its own technical and physical capabilities to determine the ability of IMRT to deliver an optimal treatment plan. This includes calculating the internal tumor motion (ideally 4DCT or equivalent techniques, treatment planning software with an up-to-date heterogeneity correction algorithm, and daily image guidance. It is crucial to optimise and individualise the therapeutic ratio for each patient during the decision of 3DCRT versus IMRT. The current literature rationalises the increasing use of IMRT, including 4D imaging plus PET/CT, and encourages the applicable knowledge-based and individualised dose escalation using advanced daily image-guided radiotherapy.
International Nuclear Information System (INIS)
Kim, Haeyoung; Lim, Do Hoon; Paik, Seung Woon; Yoo, Byung Chul; Koh, Kwang Gheol; Lee, Joon Hyoek; Choi, Moon Seok; Park, Won; Park, Hee Chul; Huh, Seung Jae; Choi, Doo Ho; Ahn, Yong Chan
2009-01-01
Background and purpose: To identify predictive factors for the development of gastroduodenal toxicity (GDT) in cirrhotic patients treated with three-dimensional conformal radiotherapy (3D-CRT) for hepatocellular carcinoma (HCC). Materials and methods: We retrospectively analyzed dose-volume histograms (DVHs) and clinical records of 73 cirrhotic patients treated with 3D-CRT for HCC. The median radiation dose was 36 Gy (range, 30-54 Gy) with a daily dose of 3 Gy. The grade of GDT was defined by the Common Toxicity Criteria Version 2. The predictive factors of grade 3 GDT were identified. Results: Grade 3 GDT was found in 9 patients. Patient's age and the percentage of gastroduodenal volume receiving more than 35 Gy (V 35 ) significantly affected the development of grade 3 GDT. Patients over 50 years of age developed grade 3 GDT more frequently than patients under 50 years of age. The risk of grade 3 GDT grew exponentially as V 35 increased. The 1-year actuarial rate of grade 3 GDT in patients with V 35 35 ≥5% (4% vs. 48%, p 35 were the most predictive factors for the development of grade 3 GDT in patients treated with RT.
International Nuclear Information System (INIS)
Zheng Aiqing; Yu Jinming; Zhao Xianguang; Wang Xuetao; Wei Guangsheng
2005-01-01
Objective: To evaluate the effect and complication of induction chemotherapy combined with three-dimensional conformal radiation therapy (3DCRT) for locally advanced non small cell lung cancer (NSCLC). Methods: Ninety-two such patients were randomized into radiation therapy alone group(RT-, 50 patients) and induction chemotherapy combined radiotherapy group (CMT-, 42 patients). The induction chemotherapy consisted of 2-4 cycles of platinum-based regimen. Results: The overall median survival time was 15 months with 12 months in the RT group and 18 months in the CMT group (P=0.014) respectively. The 1-year overall survival rates were 48.6% and 71.2% in RT and CMT group, respectively (P=0.004). The 2-year survival rates were 20.8% and 37.6% in RT and CMT group, respectively (P=0.041). Treatment was well tolerated and the toxicities were similar in either group. Conclusion: The addition of induction chemotherapy to 3DCRT takes a survival advantage over 3DCRT alone for Stage III NSCLC without increasing toxicities. (authors)
Energy Technology Data Exchange (ETDEWEB)
Richert, John D [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA 70803-4001 (United States); Hogstrom, Kenneth R [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA 70803-4001 (United States); Fields, Robert S [Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809-3482 (United States); II, Kenneth L Matthews [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA 70803-4001 (United States); Boyd, Robert A [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, LA 70803-4001 (United States)
2007-05-07
The purpose of the present study is to demonstrate that the use of an electron applicator with energy-dependent source-to-collimator distances (SCDs) will significantly improve the dose homogeneity for abutted electron fields in segmented-field electron conformal therapy (ECT). Multiple Coulomb scattering theory was used to calculate and study the P{sub 80-20} penumbra width of off-axis dose profiles as a function of air gap and depth. Collimating insert locations with air gaps (collimator-to-isocenter distance) of 5.0, 7.5, 11.5, 17.5 and 19.5 cm were selected to provide equal P{sub 80-20} at a depth of 1.5 cm in water for energies of 6, 9, 12, 16 and 20 MeV, respectively, for a Varian 2100EX radiation therapy accelerator. A 15 x 15 cm{sup 2} applicator was modified accordingly, and collimating inserts used in the variable-SCD applicator for segmented-field ECT were constructed with diverging edges using a computer-controlled hot-wire cutter, which resulted in 0.27 mm accuracy in the abutted edges. The resulting electron beams were commissioned for the pencil-beam algorithm (PBA) on the Pinnacle{sup 3} treatment planning system. Four hypothetical planning target volumes (PTVs) and one patient were planned for segmented-field ECT using the new variable-SCD applicator, and the resulting dose distributions were compared with those calculated for the identical plans using the conventional 95 cm SCD applicator. Also, a method for quality assurance of segmented-field ECT dose plans using the variable-SCD applicator was evaluated by irradiating a polystyrene phantom using the treatment plans for the hypothetical PTVs. Treatment plans for all four of the hypothetical PTVs using the variable-SCD applicator showed significantly improved dose homogeneity in the abutment regions of the segmented-field ECT plans. This resulted in the dose spread (maximum dose-minimum dose), {sigma}, and D{sub 90-10} in the PTV being reduced by an average of 32%, 29% and 32%, respectively
(2 + 1)-dimensional interacting model of two massless spin-2 fields as a bi-gravity model
Hoseinzadeh, S.; Rezaei-Aghdam, A.
2018-06-01
We propose a new group-theoretical (Chern-Simons) formulation for the bi-metric theory of gravity in (2 + 1)-dimensional spacetime which describe two interacting massless spin-2 fields. Our model has been formulated in terms of two dreibeins rather than two metrics. We obtain our Chern-Simons gravity model by gauging mixed AdS-AdS Lie algebra and show that it has a two dimensional conformal field theory (CFT) at the boundary of the anti de Sitter (AdS) solution. We show that the central charge of the dual CFT is proportional to the mass of the AdS solution. We also study cosmological implications of our massless bi-gravity model.
Energy Technology Data Exchange (ETDEWEB)
Olofsen-van Acht, M.J.J.; Quint, S.; Seven, M.; Berg, H.A. van den; Levendag, P.C. [University Hospital Rotterdam (Netherlands). Dept. of Radiation Oncology; Santvoort, J.P.C. van [University Hospital Rotterdam (Netherlands). Subdivision of Clinical Physics; Logmans, A. [University Hospital Rotterdam (Netherlands). Dept. of Gynecologic Oncology
1999-09-01
Purpose: Reduction of irradiated small bowel volume, using a conformal three-dimensional treatment planning technique in postoperative radiotherapy of cervical cancer patients. Patients and Methods: Large gynecological treatment fields including the para-aortic nodes were analyzed in 15 patients. A conventional treatment plan with anterior and posterior (AP-PA) parallel opposed fields and a 3D 4-field conformal radiotherapy plan with a central blocking of small bowel were compared for each patient. Dose-volume histograms and dose parameters were established. Because of the tolerance constraints of the small bowel, the cumulative dose applied to the target was 48.6 Gy. Results: The mean Tumor Control Probability (TCP) values for both the conventional and the conformal technique were 0.60 and 0.61, respectively, with ranges of 0.56 to 0.67 and 0.57 to 0.66, respectively. The mean volume receiving 95% or more of the prescribed dose (V95) of the small bowel was 47.6% (32.5 to 66.3%) in the AP-PA technique and 14.9% (7.0 to 22.5%) in the conformal technique (p<0.001), indicating a significant reduction in irradiated volume of small bowel in the higher dose range. The mean Normal Tissue Complication Probability (NTCP) decreased from 0.11 to 0.03 with the conformal plan. In patients who received a pedicled omentoplasty during surgery, the mean V95 for small bowel could be reduced to 8.5% (7.0 to 9.9%). The mean median dose to the kidneys was only slightly elevated in the conformal treatment. Especially the mean dose to the right kidney in conventional vs conformal treatment was 3.3 vs 7.9 Gy. The mean near-minimum dose (D95) to the rectosigmoid decreased from 48.4 to 30.1 Gy in the conformal plan compared to the conventional plan. Conclusion: The small bowel dose can be significantly reduced with 3D treatment planning, particularly if a predicled omentoplasty is performed. This allows dose escalation to the tumor region without unacceptable toxicity for the small bowel
DEFF Research Database (Denmark)
Kiriy, N.; Kiriy, A.; Bocharova, V.
2004-01-01
by the pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) technique was found to be Sigmamu(min) = 3.9 x 10(-3) cm(2) V-1 s(-1), which is comparable with the PR-TRMC mobility found for alpha,omega-DH6T. The field-effect mobility (FEM) of beta,beta'-DH6T was found to be on the order of 10(-5) cm(2......) V-1 s(-1), which is considerably less than the FEM of alpha,omega-DH6T. To understand the reason for such poor macroscopic electrical properties, the conformation and the molecular packing of beta,beta'-DH6T were systematically studied by means of UV-vis spectroscopy, scanning electron microscopy...... less dense crystalline packing than alpha,omega-DH6T. In contrast to the almost upright orientation of alpha,omega-DH6T molecules against the substrate (tilt angle about 68), the long axis of beta,beta'-DH6T molecules and the surface plane form an angle of similar to20degrees. Thus, the crystalline...
Orbifold constructions and the classification of self-dual c=24 conformal field theories
International Nuclear Information System (INIS)
Montague, P.S.
1994-01-01
We discuss questions arising from the work of Schellekens [A.N. Schellekens, Phys. Lett. B 277 (1992) 277; Meromorphic c=24 conformal field theories, CERN-TH.6478/92, 1992.] After introducing the concept of complementary representations, we examine Z 2 -orbifold constructions in general, and propose a technique for identifying the orbifold theory without knowledge of its explicit construction. This technique is then generalised to twists of order 3, 5 and 7, and we proceed to apply our considerations to the FKS constructions H (Λ) (Λ an even self-dual lattice) and the reflection-twisted orbifold theories and H ;(Λ), which together remain the only c=24 theories which have so far been proven to exist [L. Dolan, P. Goddard and P. Montague, Nucl. Phys. B 338 (1990) 529.] We also make, in the course of our arguments, some comments on the automorphism groups of the theories H (Λ) and and H ;(Λ), and of meromorphic theories in general, introducing the concept of deterministic theories. ((orig.))
Belletête, J.; Gainutdinov, A. M.; Jacobsen, J. L.; Saleur, H.; Vasseur, R.
2017-12-01
The relationship between bulk and boundary properties is one of the founding features of (rational) conformal field theory (CFT). Our goal in this paper is to explore the possibility of having an equivalent relationship in the context of lattice models. We focus on models based on the Temperley-Lieb algebra, and use the concept of ‘braid translation’, which is a natural way, in physical terms, to ‘close’ an open spin chain by adding an interaction between the first and last spins using braiding to ‘bring’ them next to each other. The interaction thus obtained is in general non-local, but has the key feature that it is expressed solely in terms of the algebra for the open spin chain—the ‘ordinary’ Temperley-Lieb algebra and its blob algebra generalization. This is in contrast with the usual periodic spin chains which involve only local interactions, and are described by the periodic Temperley-Lieb algebra. We show that for the restricted solid-on-solid models, which are known to be described by minimal unitary CFTs (with central charge ccontent in terms of the irreducibles is the same, as well as the spectrum, but the detailed structure (like logarithmic coupling) is profoundly different. This carries over to the continuum limit. The situation is similar for the sl(2\\vert 1) case. The problem of relating bulk and boundary lattice models for LCFTs thus remains open.
Integrable models in 1+1 dimensional quantum field theory
International Nuclear Information System (INIS)
Faddeev, Ludvig.
1982-09-01
The goal of this lecture is to present a unifying view on the exactly soluble models. There exist several reasons arguing in favor of the 1+1 dimensional models: every exact solution of a field-theoretical model can teach about the ability of quantum field theory to describe spectrum and scattering; some 1+1 d models have physical applications in the solid state theory. There are several ways to become acquainted with the methods of exactly soluble models: via classical statistical mechanics, via Bethe Ansatz, via inverse scattering method. Fundamental Poisson bracket relation FPR and/or fundamental commutation relations FCR play fundamental role. General classification of FPR is given with promizing generalizations to FCR
Primary decomposition of zero-dimensional ideals over finite fields
Gao, Shuhong; Wan, Daqing; Wang, Mingsheng
2009-03-01
A new algorithm is presented for computing primary decomposition of zero-dimensional ideals over finite fields. Like Berlekamp's algorithm for univariate polynomials, the new method is based on the invariant subspace of the Frobenius map acting on the quotient algebra. The dimension of the invariant subspace equals the number of primary components, and a basis of the invariant subspace yields a complete decomposition. Unlike previous approaches for decomposing multivariate polynomial systems, the new method does not need primality testing nor any generic projection, instead it reduces the general decomposition problem directly to root finding of univariate polynomials over the ground field. Also, it is shown how Groebner basis structure can be used to get partial primary decomposition without any root finding.
Directory of Open Access Journals (Sweden)
Frauendiener Jörg
2000-08-01
Full Text Available The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, ``conformal infinity'' is related with almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved out of physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation and how it lends itself very naturally to solve radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
Frauendiener, Jörg
2004-01-01
The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, "conformal infinity" is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
Directory of Open Access Journals (Sweden)
Frauendiener Jörg
2004-01-01
Full Text Available The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, 'conformal infinity' is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
Three-dimensional polarization states of monochromatic light fields.
Azzam, R M A
2011-11-01
The 3×1 generalized Jones vectors (GJVs) [E(x) E(y) E(z)](t) (t indicates the transpose) that describe the linear, circular, and elliptical polarization states of an arbitrary three-dimensional (3-D) monochromatic light field are determined in terms of the geometrical parameters of the 3-D vibration of the time-harmonic electric field. In three dimensions, there are as many distinct linear polarization states as there are points on the surface of a hemisphere, and the number of distinct 3-D circular polarization states equals that of all two-dimensional (2-D) polarization states on the Poincaré sphere, of which only two are circular states. The subset of 3-D polarization states that results from the superposition of three mutually orthogonal x, y, and z field components of equal amplitude is considered as a function of their relative phases. Interesting contours of equal ellipticity and equal inclination of the normal to the polarization ellipse with respect to the x axis are obtained in 2-D phase space. Finally, the 3×3 generalized Jones calculus, in which elastic scattering (e.g., by a nano-object in the near field) is characterized by the 3-D linear transformation E(s)=T E(i), is briefly introduced. In such a matrix transformation, E(i) and E(s) are the 3×1 GJVs of the incident and scattered waves and T is the 3×3 generalized Jones matrix of the scatterer at a given frequency and for given directions of incidence and scattering.
Nonstandard approximation schemes for lower dimensional quantum field theories
International Nuclear Information System (INIS)
Fitzpatrick, D.A.
1981-01-01
The purpose of this thesis has been to apply two different nonstandard approximation schemes to a variety of lower-dimensional schemes. In doing this, we show their applicability where (e.g., Feynman or Rayleigh-Schroedinger) approximation schemes are inapplicable. We have applied the well-known mean-field approximation scheme by Guralnik et al. to general lower dimensional theories - the phi 4 field theory in one dimension, and the massive and massless Thirring models in two dimensions. In each case, we derive a bound-state propagator and then expand the theory in terms of the original and bound-state propagators. The results obtained can be compared with previously known results thereby show, in general, reasonably good convergence. In the second half of the thesis, we develop a self-consistent quantum mechanical approximation scheme. This can be applied to any monotonic polynomial potential. It has been applied in detail to the anharmonic oscillator, and the results in several analytical domains are very good, including extensive tables of numerical results
On the conformal transformations in the massless Thirring model
International Nuclear Information System (INIS)
Hadjiivanov, L.K.; Mikhov, S.G.; Stoyanov, D.T.
1977-01-01
On the basis of solutions for the massless scalar field in the two dimensional space-time the fields satisfying the renormalized Thirring equation are constructed. Both infinitesimal and global transformations with respect to the two-dimensional conformal group for these fields are obtained. The latter do not coincide with the standard ones. The renormalized Thirring equation is proved to be covariant under infinitesimal conformal group transformations as well as under the global transformations belonging to the universal covering of the conformal group
Energy Technology Data Exchange (ETDEWEB)
Yang, Oh Nam [Gangneung Asan Hospital, Gangneung (Korea, Republic of); Yang, Oh Nam; Lim, Cheong Hwan [Hanseo Univ., Seosan (Korea, Republic of)
2012-12-15
Intensity-modulated radiotherapy(IMRT) have the ability to provide better dose conformity and sparing of critical normal tissues than three-dimensional radiotherapy(3DCRT). Especially, with the benefit of health insurance in 2011, its use now increasingly in many modern radiotherapy departments. Also the use of linear accelerator with high-energy photon beams over 10 MV is increasing. As is well known, these linacs have the capacity to produce photoneutrons due to photonuclear reactions in materials with a large atomic number such as the target, flattening filters, collimators, and multi-leaf collimators(MLC). MLC-based IMRT treatments increase the monitor units and the probability of production of photoneutrons from photon-induced nuclear reactions. The purpose of this study is to quantitatively evaluate the dose of photoneutrons produced from 3DCRT and IMRT technique for Rando phantom in cervical cancer. We performed the treatment plans with 3DCRT and IMRT technique using Rando phantom for treatment of cervical cancer. An Rando phantom placed on the couch in the supine position was irradiated using 15 MV photon beams. Optically stimulated luminescence dosimeters(OSLD) were attached to 4 different locations (abdomen, chest, head and neck, eyes) and from center of field size and measured 5 times each of locations. Measured neutron dose from IMRT technique increased by 9.0, 8.6, 8.8, and 14 times than 3DCRT technique for abdomen, chest, head and neck, and eyes, respectively. When using IMRT with 15 MV photon beams, the photoneutrons contributed a significant portion on out-of-field. It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, it is need to provide the additional safe shielding on a linear accelerator and should therefore reduce the out-of-field dose.
International Nuclear Information System (INIS)
Yang, Oh Nam; Yang, Oh Nam; Lim, Cheong Hwan
2012-01-01
Intensity-modulated radiotherapy(IMRT) have the ability to provide better dose conformity and sparing of critical normal tissues than three-dimensional radiotherapy(3DCRT). Especially, with the benefit of health insurance in 2011, its use now increasingly in many modern radiotherapy departments. Also the use of linear accelerator with high-energy photon beams over 10 MV is increasing. As is well known, these linacs have the capacity to produce photoneutrons due to photonuclear reactions in materials with a large atomic number such as the target, flattening filters, collimators, and multi-leaf collimators(MLC). MLC-based IMRT treatments increase the monitor units and the probability of production of photoneutrons from photon-induced nuclear reactions. The purpose of this study is to quantitatively evaluate the dose of photoneutrons produced from 3DCRT and IMRT technique for Rando phantom in cervical cancer. We performed the treatment plans with 3DCRT and IMRT technique using Rando phantom for treatment of cervical cancer. An Rando phantom placed on the couch in the supine position was irradiated using 15 MV photon beams. Optically stimulated luminescence dosimeters(OSLD) were attached to 4 different locations (abdomen, chest, head and neck, eyes) and from center of field size and measured 5 times each of locations. Measured neutron dose from IMRT technique increased by 9.0, 8.6, 8.8, and 14 times than 3DCRT technique for abdomen, chest, head and neck, and eyes, respectively. When using IMRT with 15 MV photon beams, the photoneutrons contributed a significant portion on out-of-field. It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, it is need to provide the additional safe shielding on a linear accelerator and should therefore reduce the out-of-field dose
Energy Technology Data Exchange (ETDEWEB)
Li, Hui-Ling, E-mail: LHL51759@126.com [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034 (China); Yang, Shu-Zheng, E-mail: szyangcwnu@126.com [Institute of Theoretical Physics, China West Normal University, Nanchong 637002 (China); Zu, Xiao-Tao, E-mail: xtzu@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China)
2017-01-10
In the framework of holography, we survey the phase structure for a higher dimensional hairy black hole including the effects of the scalar field hair. It is worth emphasizing that, not only black hole entropy, but also entanglement entropy and two point correlation function exhibit the Van der Waals-like phase transition in a fixed scalar charge ensemble. Furthermore, by making use of numerical computation, we show that the Maxwell's equal area law is valid for the first order phase transition. In addition, we also discuss how the hair parameter affects the black hole's phase transition.
Desingularization strategies for three-dimensional vector fields
Torres, Felipe Cano
1987-01-01
For a vector field #3, where Ai are series in X, the algebraic multiplicity measures the singularity at the origin. In this research monograph several strategies are given to make the algebraic multiplicity of a three-dimensional vector field decrease, by means of permissible blowing-ups of the ambient space, i.e. transformations of the type xi=x'ix1, 2s. A logarithmic point of view is taken, marking the exceptional divisor of each blowing-up and by considering only the vector fields which are tangent to this divisor, instead of the whole tangent sheaf. The first part of the book is devoted to the logarithmic background and to the permissible blowing-ups. The main part corresponds to the control of the algorithms for the desingularization strategies by means of numerical invariants inspired by Hironaka's characteristic polygon. Only basic knowledge of local algebra and algebraic geometry is assumed of the reader. The pathologies we find in the reduction of vector fields are analogous to pathologies in the pro...
International Nuclear Information System (INIS)
Nebel, R.A.; Hagenson, R.L.; Moses, R.W.; Krakowski, R.A.
1980-01-01
Conceptual fusion reactor designs of the Reversed-Field Pinch Reactor (RFPR) have been based on profile-averaged zero-dimensional (point) plasma models. The plasma response/performance that has been predicted by the point plasma model is re-examined by a comprehensive one-dimensional (radial) burn code that has been developed and parametrically evaluated for the RFPR. Agreement is good between the zero-dimensional and one-dimensional models, giving more confidence in the RFPR design point reported previously from the zero-dimensional analysis
International Nuclear Information System (INIS)
Hooft, G.
2012-01-01
The dynamical degree of freedom for the gravitational force is the metric tensor, having 10 locally independent degrees of freedom (of which 4 can be used to fix the coordinate choice). In conformal gravity, we split this field into an overall scalar factor and a nine-component remainder. All unrenormalizable infinities are in this remainder, while the scalar component can be handled like any other scalar field such as the Higgs field. In this formalism, conformal symmetry is spontaneously broken. An imperative demand on any healthy quantum gravity theory is that black holes should be described as quantum systems with micro-states as dictated by the Hawking-Bekenstein theory. This requires conformal symmetry that may be broken spontaneously but not explicitly, and this means that all conformal anomalies must cancel out. Cancellation of conformal anomalies yields constraints on the matter sector as described by some universal field theory. Thus black hole physics may eventually be of help in the construction of unified field theories. (author)
Conformal symmetries of FRW accelerating cosmologies
International Nuclear Information System (INIS)
Kehagias, A.; Riotto, A.
2014-01-01
We show that any accelerating Friedmann–Robertson–Walker (FRW) cosmology with equation of state w<−1/3 (and therefore not only a de Sitter stage with w=−1) exhibits three-dimensional conformal symmetry on future constant-time hypersurfaces if the bulk theory is invariant under bulk conformal Killing vectors. We also offer an alternative derivation of this result in terms of conformal Killing vectors and show that long wavelength comoving curvature perturbations of the perturbed FRW metric are just conformal Killing motions of the FRW background. We then extend the boundary conformal symmetry to the bulk for accelerating cosmologies. Our findings indicate that one can easily generate perturbations of scalar fields which are not only scale invariant, but also fully conformally invariant on super-Hubble scales. Measuring a scale-invariant power spectrum for the cosmological perturbation does not automatically imply that the universe went through a de Sitter stage
Character relations and replication identities in 2d Conformal Field Theory
Energy Technology Data Exchange (ETDEWEB)
Bantay, P. [Institute for Theoretical Physics, Eötvös Loránd University,H-1117 Budapest, Pázmány P.s. 1/A (Hungary)
2016-10-05
We study replication identities satisfied by conformal characters of a 2D CFT, providing a natural framework for a physics interpretation of the famous Hauptmodul property of Monstrous Moonshine, and illustrate the underlying ideas in simple cases.
Conformational transformations induced by the charge-curvature interaction: Mean-field approach
DEFF Research Database (Denmark)
Gaididei, Yu B.; Christiansen, Peter Leth; Zakrzewski, W.J.
2006-01-01
A simple phenomenological model for describing the conformational dynamics of biological macromolecules via the nonlinearity-induced instabilities is proposed. It is shown that the interaction between charges and bending degrees of freedom of closed molecular aggregates may act as drivers giving ...... impetus to conformational dynamics of biopolymers. It is demonstrated that initially circular aggregates may undergo transformation to polygonal shapes and possible application to aggregates of bacteriochlorophyl a molecules is considered....
Edler, J.; Hamm, P.
2003-08-01
Two-dimensional infrared (2D-IR) spectroscopy is applied to investigate acetanilide, a molecular crystal consisting of quasi-one-dimensional hydrogen bonded peptide units. The amide-I band exhibits a double peak structure, which has been attributed to different mechanisms including vibrational self-trapping, a Fermi resonance, or the existence of two conformational substates. The 2D-IR spectrum of crystalline acetanilide is compared with that of two different molecular systems: (i) benzoylchloride, which exhibits a strong symmetric Fermi resonance and (ii) N-methylacetamide dissolved in methanol which occurs in two spectroscopically distinguishable conformations. Both 2D-IR spectra differ significantly from that of crystalline acetanilide, proving that these two alternative mechanisms cannot account for the anomalous spectroscopy of crystalline acetanilide. On the other hand, vibrational self-trapping of the amide-I band can naturally explain the 2D-IR response.
International Nuclear Information System (INIS)
Eisbruch, Avraham; Marsh, Lon H.; Martel, Mary K.; Ship, Jonathan A.; Haken, Randall ten; Pu, Anthony T.; Fraass, Benedick A.; Lichter, Allen S.
1998-01-01
Purpose: Conformal treatment using static multisegmental intensity modulation was developed for patients requiring comprehensive irradiation for head and neck cancer. The major aim is sparing major salivary gland function while adequately treating the targets. To assess the adequacy of the conformal plans regarding target coverage and dose homogeneity, they were compared with standard irradiation plans. Methods and Materials: Fifteen patients with stage III/IV head and neck cancer requiring comprehensive, bilateral neck irradiation participated in this study. CT-based treatment plans included five to six nonopposed fields, each having two to four in-field segments. Fields and segments were devised using beam's eye views of the planning target volumes (PTVs), noninvolved organs, and isodose surfaces, to achieve homogeneous dose distribution that encompassed the targets and spared major salivary gland tissue. For comparison, standard three-field radiation plans were devised retrospectively for each patient, with the same CT-derived targets used for the clinical (conformal) plans. Saliva flow rates from each major salivary gland were measured before and periodically after treatment. Results: On average, the minimal dose to the primary PTVs in the conformal plans [95.2% of the prescribed dose, standard deviation (SD) 4%] was higher than in the standard plans (91%, SD 7%; p = 0.02), and target volumes receiving <95% or <90% of the prescribed dose were smaller in the conformal plans (p = 0.004 and 0.02, respectively). Similar advantages of the conformal plans compared to standard plans were found in ipsilateral jugular nodes PTV coverage. The reason for underdosing in the standard treatment plans was primarily failure of electron beams to fully encompass targets. No significant differences were found in contralateral jugular or posterior neck nodes coverage. The minimal dose to the retropharyngeal nodes was higher in the standard plans. However, all conformal plans